Reactivity of Ortho-Palladated Phenol Derivatives with Unsaturated

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Reactivity of Ortho-Palladated Phenol Derivatives with Unsaturated Molecules. 1. Insertion of CO, Isocyanides, Alkenes, and Alkynes. CO/Alkene, Alkyne/Isocyanide, and Isocyanide/Alkene Sequential Insertion Reactions† Jose´ Vicente,*,‡ Jose´-Antonio Abad,*,‡ Walter Fo¨rtsch, and Marıá-Jose´ Lo´pez-Saéz Grupo de Quı´mica Organometa´ lica, Departamento de Quı´mica Inorga´ nica, Facultad de Quı´mica, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain

Peter G. Jones*,§ Institut fu¨ r Anorganische und Analytische Chemie der Technischen Universita¨ t, Postfach 3329, 38023 Braunschweig, Germany Received May 28, 2004 Reactions of HOC6H4I-2 with [Pd2(dba)3]‚dba (“Pd(dba)2”; dba ) dibenzylideneacetone) and N-donor ligands (4,4′-di-tert-butyl-2,2′-bipyridine (dtbbpy), N,N,N′,N′-tetramethylethylenediamine (tmeda), 1,10-phenanthroline (phen)) lead to the arylpalladium complexes [Pd(C6H4OH-2)I(L2)] (L2 ) dtbbpy (1a′), tmeda (1a′′), phen (1a′′′)). Complexes 1a′ and 1a′′ react with CO to give the aroyl derivatives [Pd{C(O)C6H4OH-2}I(dtbbpy)] (2a′) and [Pd{C(O)C6H4OH-2}I(tmeda)] (2a′′), respectively. The compound 1a′ reacts with isocyanides RNC (R ) 2,6-dimethylphenyl (Xy), tBu) to give [Pd{C(dNR)C6H4OH-2}I(dtbbpy)] (R ) Xy (3a′Xy), tBu (3a′tBu)). The reactions of complexes [Pd(C6H4OX-2)I(bpy)] (X ) H (1a), C(O)Me (1b)) and 1a′ with alkynes RCtCR give the alkenyl complexes [Pd{CRdCR(C6H4OX-2)}I(L2)] (X ) H, R ) CO2Me, L2 ) bpy (4a), dtbbpy (4a′); X ) C(O)Me, L2 ) bpy, R ) CO2Me (4b), Ph (4b*)) through the insertion of the alkyne molecule into the palladium-carbon bond. When complex 1b reacts with PhCtCPh and TlOTf (1:3:1 molar ratio), the diinserted species [Pd{CPhdCPh-CPhdCPh(C6H4OC(O)Me-2)}(OTf)(bpy)] (5) is formed. Complexes 1a and 1a′ insert 1,5-cyclooctadiene (C8H12) in the presence of TlOTf to give [Pd(η1(C):η2(C,C)-C8H12C6H4OH-2)(L2)]TfO (L2 ) bpy (6a), dtbbpy (6a′)). When similar reactions were carried out with 1a and 2,5-norbornadiene (C7H8), dicyclopentadiene (C10H12), or norbornene (C7H10), polyinserted species were obtained. The FAB+ mass spectra of these species give peaks for (M - OTf)+, where M ) Pd{(C7H8)nC6H4OH-2}(bpy) (n ) 1-10 or 1-18, depending on the amounts of diolefin used), Pd{(C10H12)nC6H4OH-2}(bpy) (n ) 1-5), and [Pd{(C7H10)nC6H4OH-2}(OTf)(bpy)] (n ) 1-11). The aroyl compound 2a reacts similarly with 2,5-norbornadiene or norbornene to give [Pd{(C7H8)nC(O)C6H4OH-2}(OTf)(bpy)] (n ) 1-10) or [Pd{(C7H10)nC(O)(C6H4OH-2)}(OTf)(bpy)] (n ) 1-10), respectively. The reaction of 4a with XyNC and TlOTf (1:1:1 molar ratio) gives [Pd{C(dNXy)C(CO2Me)dC(CO2Me)(C6H4OH-2)}(bpy)]TfO (7aXy), which is the result of the successive insertion of an alkyne and an isocyanide into a palladium-carbon bond. The reaction of 4a with a 4-fold excess of isocyanide gives dimethyl 2-(2,6-dimethylphenyl)imino-2H-chromene-3,4-dicarboxylate iminecoumarin (8), a result of the sequential insertion of alkyne and isonitrile into the Pd-C bond, followed by a depalladation process, as the only characterizable product. When 4b* reacts with XyNC and TlOTf [Pd{CPhdCPh(C6H4OC(O)Me-2)}(CNXy)(bpy)]TfO (9b*Xy) is obtained. The compounds 3atBu, [Pd{C(dNXy)(C6H4OC(O)Me-2)}I(bpy)] (3bXy), and [Pd{C(dNXy)(C6H4CN-2)}I(bpy)] (3cXy) react with 2,5-norbornadiene or dicyclopentadiene in the presence of TlOTf to give the isocyanide/alkene inserted complexes [Pd{κ2C,N-(C7H8)C(dNR)(C6H4X-2)}(bpy)]TfO (R ) tBu, X ) OH (10atBu); R ) Xy, X ) MeCO2 (10bXy), CN (10cXy)) or [Pd{κ2-C,N-(C10H12)C(dNXy)(C6H4O2CMe-2)}(bpy)]TfO (10b*Xy), respectively. Other isocyanide/alkene sequentially inserted complexes can be obtained by reaction of trans-[Pd{C(dNXy)(C6H4X-2)}I(CNXy)2] (X ) OH (11aXy), CN (11cXy)) with 2,5-norbornadiene or norbornene and TlOTf, which renders cis-[Pd{κ2C,N-(C7H8)C(dNXy)(C6H4X-2)}(CNXy)2]TfO (X ) OH (12aXy), CN (12c′Xy)) or cis-[Pd{κ2C,N-(C7H10)C(dNXy)(C6H4OH-2)}(CNXy)2]TfO (12a*Xy), respectively. The crystal and molecular structures of 2a′′, 4a′, 4b, 6a, 6a′, 10atBu, 12aXy, and 12c′Xy have been determined.

Introduction The insertion of unsaturated molecules into metalcarbon bonds constitutes a topic of current interest,1 † Dedicado a la memoria del Dr. Juan Carlos del Amo, fallecido en el atentado terrorista ocurrido en Madrid el 11 de Marzo de 2004. Dedicated to the memory of Dr. Juan Carlos del Amo, killed in the terrorist act that occurred in Madrid on March 11th, 2004. ‡ E-mail: [email protected] (J.V.); [email protected] (J.-A.A). WWW: http://www.um.es/gqo/. § E-mail: [email protected].

particularly those involving palladium species because of their important applications in organic synthesis.2-4 Thus, the study of the insertion of alkenes into the palladium-carbon bond has attracted a great deal of interest, since it constitutes a key step in very important processes such as the Heck reaction,3-5 the palladiumcatalyzed oligo-6 or polymerization of olefins,7,8 annulation of cyclic and bicyclic alkenes,9 or double arylation of olefins.10,11 However, few examples of organopalla-

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Ortho-Palladated Phenol Derivatives

dium complexes resulting after the insertion of an alkene into an acyl- or aryl-palladium bond have been isolated.12 In this paper, we study the reactions of insertion into the C-Pd bond of some ortho-palladated phenol derivatives and the isolation of the products of monoinsertion of 1,5-cyclooctadiene, the polyinsertion of norbornadiene, norbornene and dicyclopentadiene, and also the insertion of carbon monoxide followed by the polyinsertion of norbornadiene and norbornene. The study of the sequential insertion of two or more unsaturated species is of interest, because such processes contitute the first steps of important copolymerization reactions. Thus, copolymerization of CO and olefins using palladium catalysts takes place through alternating insertion of olefins and CO into the palladiumcarbon bond, and it constitutes a promising source of very interesting polymers.8,13,14 Palladium-catalyzed organic syntheses involving aryl halides or triflates and alkynes constitute very useful routes of preparation, for example, of carbacycles or heterocycles.9,15-18 In these reactions, alkenylpalladium complexes are intermediates that, in some cases, can be isolated after mono-,19-24 di-,20,21,25,26 or polyinsertion23,24,27 of alkynes into arylpalladium complexes. We report here mono- and diinsertion reactions of internal alkynes into arylpalladium complexes and also, for the first time, products resulting after a monoinsertion reaction of an alkyne followed by the insertion of an isocyanide, i.e., alkyne/isocyanide sequential insertion products. We have reported the diinsertion of an alkyne into an orthopalladated benzylamine followed by the monoinsertion of isocyanides, i.e., alkyne/alkyne/isocyanide sequential insertion reactions.26 Isocyanide/alkyne sequential insertions occur by reacting some methylpalladium complexes with (2-(trimethylsilyl)ethynyl)aryl (1) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Applications of Organotransition Metal Chemistry; University Science Books: Mill Valley, CA, 1987. van Leeuwen, P. W. N. M.; van Koten, G. An Integrated Approach to Homogeneous, Heterogeneous and Industrial Catalysis; Elsevier: Amsterdam, 1993. (2) Ryabov, A. D. Synthesis 1985, 233. (3) Heck, R. F. Palladium Reagents in Organic Synthesis; Academic Press: New York, 1985. (4) J. Tsuji, Palladium Reagents and Catalysts; Wiley: Chichester, U.K., 1995. (5) Whitcombe, N. J.; Hii, K. K.; Gibson, S. E. Tetrahedron 2001, 57, 7449. Crisp, G. T. Chem. Soc. Rev. 1998, 27, 427. Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100, 3009. (6) Shi, P. Y.; Liu, Y. H.; Peng, S. M.; Liu, S. T. Organometallics 2002, 21, 3203. DiRenzo, G. M.; White, P. S.; Brookhart, M. J. Am. Chem. Soc. 1996, 118, 6225. (7) Johnson, L. K.; Killian, C. M.; Brookhart, M. J. Am. Chem. Soc. 1995, 117, 6414. Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100, 1169. Tempel, D. J.; Johnson, L. K.; Huff, R. L.; White, P. S.; Brookhart, M. J. Am. Chem. Soc. 2000, 122, 6686. Mecking, S. Angew. Chem., Int. Ed. 2001, 40, 534. Hennis, A. D.; Polley, J. D.; Long, G. S.; Sen, A.; Yandulov, D.; Lipian, J.; Benedikt, G. M.; Rhodes, L. F.; Huffman, J. Organometallics 2001, 20, 2802. (8) Abu-Surrah, A.; Rieger, B. Angew. Chem., Int. Ed. Engl. 1996, 35, 2475. Mecking, S.; Johnson, L. K.; Wang, L.; Brookhart, M. J. Am. Chem. Soc. 1998, 120, 888. (9) Larock, R. C. J. Organomet. Chem. 1999, 576, 111. (10) Catellani, M.; Cugini, F.; Bocelli, G. J. Organomet. Chem. 1999, 584, 63. (11) Catellani, M.; Frignani, F.; Rangoni, A. Angew. Chem., Int. Ed. Engl. 1997, 36, 119. Saito, K.; Ono, K.; Sano, M.; Kiso, S.; Takeda, T. Heterocycles 2002, 57, 1781. (12) Li, C. S.; Jou, D. C.; Cheng, C. H. Organometallics 1993, 12, 3945. Albeniz, A. C.; Espinet, P.; Lin, Y. S.; Orpen, A. G.; Martin, A. Organometallics 1996, 15, 5003. Albeniz, A. C.; Espinet, P.; Lin, Y. S. Organometallics 1996, 15, 5010. Shen, H.; Jordan, R. F. Organometallics 2003, 22, 1878. Catellani, M.; Mealli, C.; Motti, E.; Paoli, P.; Perez-Carrenõ, E.; Pregosin, P. S. J. Am. Chem. Soc. 2002, 124, 4336.

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agents camptothecins and homocamptothecins, including the silatecans DB-91 and DB-67, currently in preclinical development,30 involved reacting aryl isocyanides with 6-iodo-N-propargylpyridones in the presence of silver carbonate and catalytic amounts of palladium acetate; the proposed mechanism includes an isocyanide/alkyne sequential insertion reaction.31 A CO/ alkyne/CO sequential insertion reaction has been recently reported.32 Insertion reactions of isocyanides into Pd-C bonds are involved in the synthesis of aminoisoindolinium salts,33,34 3-imino-2-phenylindazolines,35 2-cyano-1-arylazonaphthalenes, 3-amino-2-arylbenzoindazoles,36 ketenimines,22,37 2,3-dihydroisoindol-1-ones,38 and other Nheterocycles39 or N-functionalized arenes.38,40 Recently, the catalytic synthesis of an amidine from bromobenzene, pyrrolidine, and tBuNC has been reported.41 Although the insertion reactions of isocyanides into the aryl-palladium bond to give iminoacyl complexes are well-known,22,26,33,38,40,42-44 sequential insertion reactions involving isocyanides are rare. Thus, in addition to the aforementioned isocyanide/alkyne sequential insertion reactions,28,29,31 intramolecular isocyanide/ alkene sequential insertions occur by reacting some methylpalladium complexes with o-alkenylphenyl iso(19) Arlen, C.; Pfeffer, M.; Bars, O.; Grandjean, D. J. Chem. Soc., Dalton Trans. 1983, 1535. Spencer, J.; Pfeffer, M.; Decian, A.; Fischer, J. J. Org. Chem. 1995, 60, 1005. Spencer, J.; Pfeffer, M.; Kyritsakas, N.; Fischer, J. Organometallics 1995, 14, 2214. (20) Maassarani, F.; Pfeffer, M.; Le Borgne, G. Organometallics 1987, 6, 2029. Maassarani, F.; Pfeffer, M.; Le Borgne, G. Organometallics 1987, 6, 2043. Maassarani, F.; Pfeffer, M.; Spencer, J.; Wehman, E. J. Organomet. Chem. 1994, 466, 265. Zhao, G.; Wang, Q.-G.; Mak, T. C. W. J. Organomet. Chem. 1999, 574, 311. Benito, M.; Lopez, C.; Morvan, X.; Solans, X.; Fontbardia, M. Dalton 2000, 4470. (21) Vicente, J.; Abad, J. A.; Fernańdez-de-Bobadilla, R.; Jones, P. G.; Ramı´rez de Arellano, M. C. Organometallics 1996, 15, 24. (22) Vicente, J.; Abad, J. A.; Shaw, K. F.; Gil-Rubio, J.; Ramı´rez de Arellano, M. C.; Jones, P. G. Organometallics 1997, 16, 4557. (23) Yagyu, T.; Osakada, K.; Brookhart, M. Organometallics 2000, 19, 2125. (24) Yagyu, T.; Hamada, M.; Osakada, K.; Yamamoto, T. Organometallics 2001, 20, 1087. (25) Albert, J.; Granell, J.; Sales, J.; Solans, X. J. Organomet. Chem. 1989, 379, 177. Lo´pez, C.; Xolans, X.; Tramuns, D. J. Organomet. Chem. 1994, 471, 265. Zhao, G.; Wang, Q. G.; Mak, T. C. W. Tetrahedron: Asymmetry 1998, 9, 2253. (26) Vicente, J.; Saura-Llamas, I.; Turpıń, J.; Ramı´rez de Arellano, M. C.; Jones, P. G. Organometallics 1999, 18, 2683. (27) Dupont, J.; Pfeffer, M.; Daran, J.-C.; Gouteron, J. J. Chem. Soc., Dalton Trans. 1988, 2421. (28) Onitsuka, K.; Segawa, M.; Takahashi, S. Organometallics 1998, 17, 4335. (29) Delis, J. G. P.; Aubel, P. G.; Vrieze, K.; van Leeuwen, P.; Veldman, N.; Spek, A. L. Organometallics 1997, 16, 4150. (30) Bom, D.; Curran, D. P.; Kruszewski, S.; Zimmer, S. G.; Thompson Strode, J.; Kohlhagen, G.; Du, W.; Chavan, A. J.; Fraley, K. A.; Bingcang, A. L.; Latus, L. J.; Pommier, Y.; Burke, T. G. J. Med. Chem. 2000, 43, 3970. (31) Curran, D. P.; Du, W. Org. Lett. 2002, 4, 3215. (32) Carfagna, C.; Gatti, G.; Mosca, L.; Paoli, P.; Guerri, A. Organometallics 2003, 23, 3967. (33) Vicente, J.; Saura-Llamas, I.; Gru¨nwald, C.; Alcaraz, C.; Jones, P. G.; Bautista, D. Organometallics 2002, 21, 3587. (34) O’Sullivan, R. D.; Parkins, A. W. J. Chem. Soc., Chem. Commun. 1984, 1165. (35) Yamamoto, Y.; Yamazaki, H. Synthesis 1976, 750. (36) Gehrig, K.; Klaus, A. J.; Rys, P. Helv. Chim. Acta 1983, 66, 2603. (37) Tanase, T.; Fukushima, T.; Nomura, T.; Yamamoto, Y.; Kobayashi, K. Inorg. Chem. 1994, 33, 32. (38) Vicente, J.; Abad, J. A.; Martıńez-Viviente, E.; Jones, P. G. Organometallics 2003, 22, 1967. (39) Albinati, A.; Pregosin, P. S.; Ruëdi, R. Helv. Chim. Acta 1985, 68, 2046. (40) Yamamoto, Y.; Yamazaki, H. Inorg. Chim. Acta 1980, 41, 229. (41) Saluste, C. G.; Whitby, R. J.; Furber, M. Angew. Chem., Int. Ed. 2000, 39, 4156.

Vicente et al.

cyanides to give (η3-indolylmethyl)palladium complexes. Treatment of these complexes with HCl or dialkylamines produced 2,3-dimethylindole or 2-methyl-3(aminomethyl)indole derivatives, respectively.45 Insertion of XyNC into Pd-Me bonds followed by treatment with norbornadiene,29,46 ethylene, propylene, allenes,29 isocyanates or isothiocyanates46,47 has been reported. We report here the first isocyanide/alkene sequential insertions into a Pd-aryl bond. In addition, we have inserted for the first time norbornene and dicyclopentadiene into iminoacylpalladium complexes. These sequential insertions are of interest because, isonitriles being isoelectronic with carbon monoxide, copolymerization of isocyanides and unsaturated substrates, mimicking that between CO and alkenes, could be feasible if appropriate reagents and conditions were found. We have recently reported the synthesis of the first ortho-palladated complexes of phenol and some of its derivatives and the study of their reactivity with carbon monoxide and isonitriles.44 Similar complexes probably play an important role in palladium-catalyzed reactions such as the formation of o-alkynylphenols, which are intermediates in the synthesis of benzofurans,48 coumarins,49 1,3-benzoxazepin-2-ones,50 benzopyrans,51 the naturally occuring tremetone,52 and others.9 We have also reported the synthesis and reactivity with isocyanides of (2-cyanoaryl)palladium complexes.43 In this paper we report a further study of the reactivity of these ortho-palladated phenol and benzonitrile derivatives, including insertion and sequential insertion reactions involving CO, isocyanides, alkenes, and alkynes, and also the first example of a palladium-mediated formation of an iminecoumarin resulting from the successive insertion of an alkyne and an isonitrile into a carbon(42) Dupont, J.; Pfeffer, M. J. Chem. Soc., Dalton Trans. 1990, 3193. Ito, Y.; Miyake, T.; Hatano, S.; Shima, R.; Ohara, T.; Suginome, M. J. Am. Chem. Soc. 1998, 120, 11880. Kim, Y.-J.; Song, S.-W.; Lee, S.-C.; Lee, S.-W.; Osakada, K.; Yamamoto, T. J. Chem. Soc., Dalton Trans. 1998, 1775; 129:81830 ca. Zografidis, A.; Polborn, K.; Beck, W.; Markies, B. A.; van Koten, G. Z. Naturforsch., Sect. B 1994, 49, 1494. Usoń, R.; Fornie´s, J.; Espinet, P.; Lalinde, E.; Jones, P. G.; Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1982, 2389. Usoń, R.; Fornie´s, J.; Espinet, P.; Lalinde, E. J. Organomet. Chem. 1983, 254, 371. Crociani, B.; Nicolini, M.; Richards, R. L. J. Organomet. Chem. 1976, 104, 259. van Baar, J. F.; Klerks, J. M.; Overbosch, P.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem. 1976, 112, 95. Yamamoto, Y.; Yamazaki, H. Inorg. Chem. 1974, 13, 438. Vicente, J.; Abad, J. A.; Frankland, A. D.; Lopez-Serrano, J.; Ramirez de Arellano, M. C.; Jones, P. G. Organometallics 2002, 21, 272. (43) Vicente, J.; Abad, J. A.; Martinez-Viviente, E.; Jones, P. G. Organometallics 2002, 21, 4454. (44) Vicente, J.; Abad, J. A.; Fo¨rtsch, W.; Jones, P. G.; Fischer, A. K. Organometallics 2001, 20, 2704. (45) Onitsuka, K.; Yamamoto, M.; Suzuki, S.; Takahashi, S. Organometallics 2002, 21, 581. (46) Owen, G. R.; Vilar, R.; White, A. J. P.; Williams, D. J. Organometallics 2002, 21, 4799. (47) Owen, G. R.; Vilar, R.; White, A. J. P.; Williams, D. J. Organometallics 2003, 22, 4511. (48) Botta, M.; Summa, V.; Corelli, F.; Dipietro, G.; Lombardi, P. Tetrahedron: Asymmetry 1996, 7, 1263. Arcadi, A.; Cacchi, S.; Delrosario, M.; Fabrizi, G.; Marinelli, F. J. Org. Chem. 1996, 61, 9280. Lu¨tjens, H.; Scammells, P. J. Tetrahedron Lett. 1998, 39, 6581. (49) Catellani, M.; Chiusoli, G. P.; Fagnola, M. C.; Solari, G. Tetrahedron Lett. 1994, 35, 5919. Catellani, M.; Chiusoli, G. P.; Marzolini, G.; Rossi, E. J. Organomet. Chem. 1996, 525, 65. Kadnikov, D. V.; Larock, R. C. Org. Lett. 2000, 2, 3643. Trost, B. M.; Toste, F. D. J. Am. Chem. Soc. 1996, 118, 6305. Trost, B. M.; Toste, F. D.; Greenman, K. J. Am. Chem. Soc. 2003, 125, 4518. (50) Bocelli, G.; Catellani, M.; Chiusoli, G. P.; Cugini, F.; Lasagni, B.; Mari, M. N. Inorg. Chim. Acta 1998, 270, 123. (51) So¨derberg, B. J.; Rector, S. R.; O’Neil, S. Tetrahedron Lett. 1999, 40, 3657. (52) Larock, R. C.; Berrios-Penã, N.; Narayanan, K. J. Org. Chem. 1990, 55, 3447.


palladium bond. To complete these studies, we have also prepared some new examples of ortho-palladated phenol compounds. Experimental Section Reactions were carried out without precautions to exclude atmospheric moisture, unless otherwise stated. The IR and C, H, and N analyses and melting point determinations were carried out as described elsewhere.53 NMR spectra were recorded on Varian Unity 300 and a Bruker Unity 200, 300, and 400 instruments. Chemical shifts were referred to TMS (1H and 13C{1H}) and PO4H3 (31P{1H}). 13C NMR assignments were made with the help of DEPT techniques. FAB MS measurements were carried out from solid samples using 3-nitrobenzyl alcohol as a matrix in a VG Autospec E apparatus. Chromatographic separations were carried out by TLC on silica gel 60 ACC (70-230 mesh). The complexes “Pd(dba)2” ([Pd2(dba)3]‚dba),3,54 [Pd(C6H4OH-2)I(bpy)] (1a), [Pd{C6H4OC(O)Me-2}I(bpy)] (1b), [Pd{C(dNtBu)(C6H4OH-2)}I(bpy)] (3atBu), [Pd{C(dNXy)(C6H4OC(O)Me-2)}I(bpy)] (3bXy), trans-[Pd{C(dNXy)(C6H4OH-2)}I(CNXy)2] (11aXy),44 [Pd{C(dNXy)(C6H4CN-2)}Br(bpy)] (3cXy), and trans-[Pd{C(dNXy)(C6H4CN-2)}Br(CNXy)2] (11cXy)43 were prepared as previously reported. [Pd(C6H4OH-2)I(dtbbpy)] (1a′). 2-Iodophenol (262 mg, 1.19 mmol) was added to a suspension of “Pd(dba)2” (288 mg, 0.5 mmol) and dtbbpy (4,4′-di-tert-butyl-2,2′-bipyridine; 268 mg, 1 mmol) in deoxygenated toluene (10 mL) under nitrogen, and the resulting mixture was stirred at 0 °C for 2.5 h. The solvent was evaporated in vacuo, the residue extracted with CH2Cl2 (20 mL), and the resulting suspension filtered over anhydrous MgSO4. The solvent was concentrated to dryness and the residue washed with boiling n-hexane (4 × 10 mL), to eliminate dba, giving an orange solid. Since this solid contained some [PdI2(dtbbpy)] (1H NMR 9.83 (d), 7.94 (s), 7.51 (dd), 1.45 (s)), it was redissolved in CH2Cl2 (2 mL), applied to a preparative TLC sheet, and eluted with CH2Cl2. The yellow band was extracted with acetone (20 mL). The resulting yellow solution was concentrated to dryness and the residue treated with CH2Cl2 (15 mL) and anhydrous MgSO4 (1 h). The resulting suspension was filtered to give a solution, which was concentrated (2 mL). Addition of n-hexane (10 mL) caused the precipitation of a solid, which was separated by filtration, washed with n-hexane (2 × 5 mL), and air-dried to give 1a′ as a yellow solid. Yield: 100 mg, 34%. Mp: 185-190 °C dec. IR (cm-1): ν(OH) 3444, 3402. 1H NMR (300 MHz, CDCl3): δ 9.47 (d, H6 or H6′ dtbbpy, 1 H, 3JHH ) 5.5 Hz), 7.98 (m, 2 H), 7.54 (dd, dtbbpy, 2 H, 3JHH ) 5.5 Hz, 4JHH ) 2 Hz), 7.32 (dd, H3 or H6 C6H4, 1 H, 3JHH ) 6 Hz, 4JHH ) 2 Hz), 7.22 (dd, H6 or H3 C6H4, 1 H, 3JHH ) 7 Hz, 4JHH ) 1 Hz), 6.94 (td, H4 or H5 C6H4, 1 H, 3JHH ) 7.5 Hz, 4JHH ) 1 Hz), 6.8-6.6 (m, 2 H), 5.82 (s, OH, 1 H), 1.44 (s, Me, 9 H), 1.38 (s, Me, 9 H). 13C{1H} NMR (75 MHz, CDCl3): δ 163.60 (C), 156.79 (C), 155.90 (C), 154.05 (C), 153.57 (C), 152.20 (CH), 149.82 (CH), 135.89 (CH), 129.31 (C), 125.05 (CH), 124.02 (CH), 123.82 (CH), 120.39 (CH), 118.52, 118.13 (CH), 113.52 (CH), 35.50 (C, tBu), 30.35 (Me), 30.20 (Me). Anal. Calcd for C24H29IN2OPd: C, 48.45; H, 4.92; N, 4.71. Found: C, 48.40; H, 5.10; N, 4.95. [Pd(C6H4OH-2)I(tmeda)] (1a′′). 2-Iodophenol (227 mg, 1.03 mmol) and tmeda (N,N,N′,N′-tetramethylenediamine; 129 µL, 0.86 mmol) were added to a suspension of “Pd(dba)2” (250 mg, 0.43 mmol) in toluene (15 mL), and the mixture was stirred under nitrogen at 0 °C for 3 h. Partial decomposition to metallic palladium was observed. The solvent was evapo(53) Vicente, J.; Abad, J. A.; Gil-Rubio, J.; Jones, P. G. Organometallics 1995, 14, 2677. (54) Yatsimirsky, A. K.; Kazankov, G. M.; Ryabov, A. D. J. Chem. Soc., Perkin Trans. 2 1992, 1295.

Organometallics, Vol. 23, No. 19, 2004 4417 rated in vacuo and the residue extracted with CH2Cl2 (20 mL). The extract was filtered over anhydrous MgSO4 and the resulting solution concentrated to ca. 2 mL. Et2O (15 mL) was added, causing the precipitation of a solid, which was filtered, washed with Et2O (3 × 5 mL), and dried to give 1a′′ as an orange solid. Yield: 61 mg, 33%. Mp: 140 °C dec. IR (cm-1): ν(OH) 3442.1H NMR (200 MHz, CDCl3): δ 7.04 (dd, C6H4, H3 or H6, 1 H, 3JHH ) 7.4 Hz, 4JHH ) 1.4 Hz), 6.84 (td, C6H4, H4 or H5, 1 H, 3JHH ) 7.4 Hz, 4JHH ) 1.4 Hz), 6.70-6.57 (m, C6H4, 2 H), 5.83 (s, OH, 1 H), 3.0-2.5 (several m, 2xCH2, 4 H), 2.73 (s, Me, 3 H), 2.70 (s, Me, 3 H), 2.46 (s, Me, 3 H), 2.23 (s, Me, 3 H). 13C{1H} NMR (75 MHz, CDCl3): δ 156.76 (C), 135.22 (CH), 127.07 (C), 124.82 (CH), 119.96 (CH), 113.25 (CH), 62.18 (CH2), 58.56 (CH2), 50.93 (Me), 50.47 (Me), 49.10 (Me), 48.32 (Me). Anal. Calcd for C12H21IN2OPd: C, 32.56; H, 4.78; N, 6.33. Found: C, 32.71; H, 4.78; N, 6.11. [Pd(C6H4OH-2)I(phen)] (1a′′′). This compound was prepared as for 1a′′ from 2-iodophenol (262 mg, 1.19 mmol), “Pd(dba)2” (288 mg, 0.5 mmol), and phen (1,10-phenanthroline; 198 mg, 1 mmol) to give orange 1a′′′. Yield: 137 mg, 54%. Mp: 185 °C. IR (cm-1): ν(OH) 3402. The complex was not sufficiently soluble for NMR studies. Anal. Calcd for C18H13IN2OPd: C, 42.67; H, 2.59; N, 5.53. Found: C, 43.04; H, 2.55; N, 5.52. [Pd{C(O)C6H4OH-2}I(dtbbpy)] (2a′). Carbon monoxide was bubbled through a solution of 1a′ (105 mg, 0.18 mmol) in CH2Cl2 (15 mL) for 30 min, and the resulting solution was stirred for a further 3 h under an atmosphere of CO. It was then concentrated (2 mL), and n-hexane (10 mL) was added, causing the precipitation of a solid, which was filtered, washed with n-hexane (2 × 5 mL), and dried to give 2a′ as an orange solid. Yield: 57 mg, 51%. Mp: 164 °C. IR (cm-1): ν(CdO) 1620. 1H NMR (300 MHz, CDCl ): δ 11.25 (s, OH, 1 H), 9.24 (d, 3 dtbbpy, 1 H, 3JHH ) 5.5 Hz), 8.88 (d, C6H4, 1 H, 3JHH ) 7.5 Hz), 7.99 (s, dtbbpy, 1 H), 7.95 (s, dtbbpy, 1 H), 7.88 (d, dtbbpy, 1 H, 3JHH ) 5.5 Hz), 7.49 (d, dtbbpy, 1 H, 3JHH ) 5 Hz), 7.36 (d, dtbbpy, 1 H, 3JHH ) 5 Hz), 7.29 (t, C6H4, 1 H, 3JHH ) 7.5 Hz), 6.90 (t, C6H4, 1 H, 3JHH ) 7.5 Hz), 6.79 (d, C6H4, 1 H, 3J 13C{1H} HH ) 7.5 Hz), 1.40 (s, Me, 9 H), 1.37 (s, Me, 9 H). NMR (75 MHz, CDCl3): δ 163.87 (C), 163.66 (C), 156.08 (C), 155.23 (C), 153.45 (C), 153.06 (C), 151.98 (CH), 149.95 (CH), 139.35 (CH), 133.95 (CH), 126.13 (C), 124.09 (CH), 123.83 (CH), 118.91 (CH), 118.78 (CH), 118.09 (CH), 116.21 (CH), 35.56 (C, tBu), 35.46 (C, tBu), 30.37 (Me), 30.20 (Me). Anal. Calcd for C25H29IN2O2Pd: C, 48.21; H, 4.69; N, 4.50. Found: C, 48.57; H, 4.67; N, 4.47. [Pd{C(O)C6H4OH-2}I(tmeda)] (2a′′). Orange 2a′′ was similarly prepared from 1a′′ (80 mg, 0.18 mmol) but using Et2O as the precipitating agent. Yield: 55 mg, 67%. Mp: 153 °C. IR (cm-1): ν(CdO) 1612. 1H NMR (400 MHz, CDCl3): δ 11.10 (s, OH, 1 H), 8.85 (d, C6H4 H6, 1 H, 3JHH ) 7.5 Hz), 7.32 (apparent t, C6H4 H4 or H5, 1 H, 3JHH ) 7.5 Hz), 7.03 (apparent t, C6H4 H4 or H5, 1 H, 3JHH ) 7.5 Hz), 6.78 (d, C6H4 H3, 1 H, 3J HH ) 8 Hz), 2.81-2.50 (several m, 3 × Me and 2 × CH2 tmeda, 13H), 2.32 (s, Me tmeda, 3 H). A singlet at 2.95 ppm corresponds to the decomposition product [PdI2(tmeda)]. 13C{1H} NMR (50 MHz, CDCl3): δ 155.65 (C), 139.58 (CH), 133.77 (CH), 124.99 (C), 118.86 (CH), 116.53 (CH), 61.79, 57.85 (CH 2), 52.11 (Me), 49.74 (Me), 48.97 (Me), 48.35 (Me). Signals at 61.59 (CH2) and 52.67 (Me) correspond to the decomposition product [PdI2(tmeda)]. Anal. Calcd for C13H21IN2O2Pd: C, 33.18; H, 4.50; N, 5.95. Found: C, 32.91; H, 4.41; N, 5.88. Single crystals were grown by slow diffusion of n-hexane into 1,2-dichloroethane solutions of 2a′′. [Pd{C(dNXy)C6H4OH-2)}I(dtbbpy)] (3a′Xy). XyNC (Xy ) 2,6-dimethylphenyl; 46 mg, 0.35 mmol) was added to a solution of 1a′ (208 mg, 0.35 mmol) in CH2Cl2 (10 mL). The resulting solution was stirred for 2 h and concentrated (ca. 2 mL), and n-hexane was added (15 mL) to precipitate a solid which was filtered, washed with n-hexane, and dried to give

4418


3a′Xy as a yellow solid. Yield: 231 mg, 92%. Mp: 224 °C dec. 1 H NMR (200 MHz, CDCl3): δ 14.68 (s, OH, 1 H), 9.28 (d, dtbbpy, 1 H, 3JHH ) 6 Hz), 8.96 (dd, 1 H, 3JHH ) 8 Hz, 4JHH ) 1.5 Hz), 8.05-7.94 (m, 3 H), 7.43-7.18 (m, 3 H), 7.04-7.64 (m, 5 H), 2.35 (Me, 3 H), 1.99 (Me, 3 H), 1.40 (tBu, 9 H), 1.39 (tBu, 9 H). 13C{1H} NMR (100 MHz, CDCl3): δ 191.97 (C), 163.79 (C), 163.33 (C), 159.15 (C), 155.54 (C), 153.20 (C), 152.51 (CH), 150.57 (CH), 148.04 (C), 137.58 (CH), 131.03 (CH), 130.85 (C), 128.17 (CH), 127.53 (CH), 126.68 (C), 125.11 (C), 123.92 (CH), 123.84 (CH), 123.69 (CH), 118.60 (CH), 117.95 (CH), 117.78 (CH), 115.97 (CH), 35.57 (C tBu), 35.40 (C tBu), 30.31 (Me, tBu), 30.20 (Me, tBu), 20.96 (Me, Xy), 19.92 (Me, Xy). Anal. Calcd for C33H38IN3OPd: C, 54.60; H, 5.28; N, 5.79. Found: C, 54.25; H, 5.35; N, 5.80. [Pd{C(dNtBu)C6H4OH-2)}I(dtbbpy)] (3a′tBu). Yellow 3a′tBu was similarly prepared from tBuNC (19 µL, 0.17 mmol) and 1a′ (100 mg, 0.17 mmol). Yield: 96 mg, 82%. Mp: 218 °C. 1 H NMR (400 MHz, CDCl3): δ 9.50 (d, dtbbpy H6 or H6′, 1 H, 3 JHH ) 5.7 Hz), 8.95 (dd, C6H4 H6, 1 H, 3JHH ) 7.9 Hz, 4JHH ) 1.6 Hz), 8.013 (s, dtbbpy H3 or H3′, 1 H), 8.010 (s, dtbbpy H3 or H3′, 1 H), 7.91 (d, dtbbpy H6 or H6′, 1 H, 3JHH ) 5.9 Hz), 7.56 (dd, dtbbpy H5 or H5′, 1 H, 3JHH ) 5.7 Hz, 4JHH ) 1.7 Hz), 7.33 (dd, dtbbpy H5 or H5′, 1 H, 3JHH ) 5.9 Hz, 4JHH ) 1.9 Hz), 7.08 (td, C6H4 H4 or H5, 1 H, 3JHH ) 8.5 Hz, 4JHH ) 1.7 Hz), 6.75 (d, C6H4 H3 or H3′, 1 H, 3JHH ) 9.0 Hz), 6.58 (td, C6H4 H4 or H5, 1 H, 3JHH ) 8.0 Hz, 4JHH ) 1.1 Hz), 1.70 (s, t BuNC, 9 H), 1.44 (s, tBu dtbbpy, 9 H), 1.39 (s, tBu dtbbpy, 9 H). 13C{1H} NMR (100 MHz, CDCl3): δ 190.83 (C), 163.86 (C), 163.70 (C), 163.63 (C), 155.46 (C), 153.22 (C), 152.42 (CH), 150.03 (CH), 139.40 (CH), 130.85 (CH), 125.51 (C), 124.14 (CH), 124.07 (CH), 118.93 (CH), 118.23 (CH), 117.60 (CH), 114.65 (CH), 55.95 (C, CNCMe3), 35.56 (C, tBu), 35.49 (C, tBu), 31.94 (Me), 30.31 (Me), 30.15 (Me). Anal. Calcd for C29H38IN3OPd: C, 51.38; H, 5.72; N, 6.20. Found: C, 51.61; H, 5.72; N, 6.20. [Pd{C(CO2Me)dC(CO2Me)(C6H4OH-2)}I(bpy)] (4a). MeO2CCtCCO2Me (82.8 µL, 0.68 mmol) was added to a solution of 1a (65 mg, 0.14 mmol) in CH2Cl2 (10 mL), and the resulting solution was stirred for 3 days. A small amount of a bright yellow precipitate could be observed after 2 days. The reaction mixture was concentrated (3 mL), and Et2O (15 mL) was added to precipitate a solid, which was filtered and washed with Et2O (15 mL) and dried under an air stream to give 4a as a bright yellow solid. Yield: 69 mg, 82%. Mp: 204 °C dec. IR (cm-1): ν(CO) 1688 cm-1. 1H NMR (300 MHz, CDCl3): δ 9.45 (d, bpy, 1 H, 3JHH ) 5 Hz), 9.07 (d, bpy, 1 H, 3JHH ) 5.5 Hz), 8.117.88 (m, bpy, 3 H), 7.64-7.61 (m, bpy H, 2 H), 7.40-7.32 (m, bpy and C6H4, 2 H), 7.08-7.02 (m, C6H4, 1 H), 6.82 (d, C6H4, 1 H, 3JHH ) 8 Hz), 6.72 (dd, C6H4, 1 H, 3JHH ) 7.5 Hz, 3JHH ) 8 Hz), 6.35 (br s, OH, 1 H), 3.85 (s, Me, 3 H), 3.70, (s, Me, 3 H). 13C{1H} NMR (50 MHz, CDCl3): δ 164.39 (CdO), 163.15 (CdO), 156.77 (C), 153.88 (C), 153.82 (C), 153.52 (CH), 152.026 (C), 150.33 (CH), 138.95 (CH), 135.84 (CH), 131.62 (CH), 126.95 (CH), 126.71 (CH), 125.32 (CH), 122.17 (CH), 120.64 (CH), 120.04 (CH), 113.81 (CH), 52.29 (Me), 51.84 (Me). Anal. Calcd for C22H19IN2O5Pd: C, 42.30; H, 3.07; N, 4.48. Found: C, 42.52; H, 2.77; N, 4.64. [Pd{C(CO2Me)dC(CO2Me)(C6H4OH-2)}I(dtbbpy)] (4a′). MeO2CCtCCO2Me (121 µL, 0,99 mmol) was added to a solution of 1a′ (130 mg, 0.22 mmol) in CH2Cl2 (10 mL), and the resulting mixture was stirred for 21 h. The solution was concentrated (ca. 2 mL) and Et2O added, precipitating nonreacted 1a′, which was filtered, washed with Et2O (2 × 5 mL), and dried (24 mg, 18%). The mother liquors were concentrated to dryness, and the residue was redissolved in CH2Cl2 (2 mL) and applied to a TLC sheet (CH2Cl2/Et2O 1/2 as eluant). The yellow band was extracted with acetone (20 mL), the resulting solution concentrated to dryness, and the corresponding residue redissolved in CH2Cl2. The solution was treated with anhydrous magnesium sulfate, and the resulting suspension was filtered, the filtrate concentrated (ca. 2 mL), and Et2O

Vicente et al. added, causing, surprisingly, the precipitation of 4a′ as a yellow solid, which was filtered, washed with Et2O (2 × 5 mL), and air-dried. Yield: 50 mg, 31%. Mp: 174 °C. IR (cm-1): ν(ΟΗ) 3376, ν(CdO) 1692, 1614 cm-1.1H NMR (400 MHz, CDCl3): δ 9.41 (d, dtbbpy, 1H , 3JHH ) 5.6 Hz), 8.99 (d, dtbbpy, 1H, 3JHH ) 6.0 Hz), 7.85 (dd, dtbbpy, 2H, 3JHH ) 5.2 Hz, 4JHH ) 1.8 Hz), 7.62 (dd, dtbbpy, 1H, 4JHH ) 6.0 Hz, 5JHH ) 2.0 Hz), 7.38 (dd, dtbbpy, 1H, 4JHH ) 6.0 Hz, 5JHH ) 2.0 Hz), 7.32 (dd, C6H4, 1H, 3JHH ) 7.6 Hz, 4JHH ) 1.4 Hz), 7.05 (td, C6H4, 1H, 3 JHH ) 6.2 Hz, 4JHH ) 1.6 Hz), 6.84 (dd, C6H4, 1H, 3JHH ) 8 Hz, 4JHH ) 1 Hz), 6.69 (td, C6H4, 1H, 3JHH ) 7.4 Hz, 4JHH ) 1.2 Hz), 6.28 (s, OH, 1H), 3.84 (s, COMe, 3H), 3.69 (s, COMe, 3H), 1.44 (s, tBu, 9H), 1.41 (s, tBu, 9H). 13C{1H} NMR (100 MHz, CDCl3): 173.15 (C), 164.28 (C), 164.18 (C), 163.82 (C), 163.58 (C), 155.57 (C), 154.28 (C), 153.82 (C), 153.33 (CH), 151.72 (CH), 131.42 (CH), 130.64 (C), 128.65 (CH), 128.10 (C), 124.01 (CH), 123.70 (CH), 119.87 (CH), 118.34 (CH), 118.03 (CH), 117.43 (CH), 52.21 (OMe), 51.78 (OMe), 35.61 (C, tBu) 35.43 (C, tBu), 30.42 (Me), 30.25 (Me). Anal. Calcd for C30H35IN2O5Pd: C, 48.90; H, 4.79; N, 3.80. Found: C, 48.97; H, 4.99; N, 3.96. Single crystals of 4a′ were grown by liquid diffusion of Et2O into solutions of the complex in acetone. [Pd{C(CO2Me)dC(CO2Me)[C6H4OC(O)Me-2]}I(bpy)] (4b). MeO2CCtCCO2Me (36.2 µL, 0.30 mmol) was added to a solution of 1b (50 mg, 0.1 mmol) in CH2Cl2 (10 mL), and the resulting mixture was stirred for 3 days. The solution was concentrated (ca. 3 mL) and Et2O added, precipitating a yellow solid, which was redissolved in the minimum amount of CH2Cl2 and purified by preparative TLC, using 1.5/1 CH2Cl2/Et2O as eluant. The yellow fraction just over the front line was collected and extracted with acetone. Evaporation to dryness rendered a residue, which was recrystallized from CH2Cl2/Et2O to give yellow 4b. Yield: 40 mg, 62%. Mp: 284 °C dec. IR (cm-1): ν(CO) 1716, 1702 cm-1. 1H NMR (300 MHz, CDCl3): δ 9.62 (d, bpy, 1 H, 3JHH ) 6 Hz), 8.85 (d, bpy, 1 H, 3JHH ) 5.5 Hz), 8.53 (m, bpy, 1 H), 7.97-7.87 (m, bpy, 3 H), 7.51-7.40 (m, bpy H, 2 H), 7.17-7.14 (m, bpy and C6H4, 2 H), 6.94-6.91 (m, C6H4, 2 H), 3.85 (s, CO2Me, 3 H), 3.67, (s, CO2Me, 3 H), 2.69 (s, 3 H, CO2Me). 13C{1H} NMR (50 MHz, CDCl3, ppm): too insoluble. Anal. Calcd for C24H21IN2O6Pd: C, 43.23; H, 3.17; N, 4.20. Found: C, 42.77; H, 2.92; N, 4.08. Single crystals were grown by slow diffusion of Et2O into CH2Cl2 solutions of 4b. [Pd{C(Ph)dC(Ph)[C6H4OC(O)Me-2]}I(bpy)] (4b*). Diphenylacetylene (102 mg, 0.57 mmol) was added to a solution of 1b (60 mg, 0.11 mmol) in CH2Cl2 (10 mL) and the mixture stirred for 3 days. The resulting solution was concentrated (ca. 3 mL), and Et2O (12 mL) was added to precipitate a yelloworange solid, consisting of the desired product and a small amount of the starting complex. A CH2Cl2 solution of this mixture was applied to a preparative TLC sheet with CH2Cl2/ Et2O 1.5/1 as eluant. The fraction containing 4b*, between the front line and the starting complex spot, was collected and eluted with acetone from the silica gel. The eluate was concentrated to dryness, the residue redissolved in CH2Cl2, and this solution finally precipitated with Et2O to give a yellow solid. Yield: 70 mg, 87%. Mp: 222 °C dec. IR (cm-1): ν(CO) 1766 cm-1. 1H NMR (200 MHz, (CD3)2CO): δ 9.49 (d, bpy, 1 H, 3JHH ) 5.5 Hz), 9.43 (d, bpy, 1 H, 3JHH ) 5.5 Hz), 8.84 (dd, bpy, 1 H, 3JHH ) 7.5 Hz, 3JHH ) 7.5 Hz), 8.47-8.10 (m, bpy and C6H5, 4 H), 7.95 (dd, bpy, 1 H, 3JHH ) 5.5 Hz, 3JHH ) 7.5 Hz), 7.62 (dd, bpy, 1 H, 3JHH ) 6.5 Hz, 3JHH ) 5.5 Hz), 7.226.85 (m, bpy and C6H5, 12 H), 6.75 (d, C6H5, 1 H, 3JHH ) 9 Hz), 2.83 (s, 3 H, Me). 13C{1H} NMR (50 MHz, CDCl3): δ 168.24 (CdO), 155.51 (C), 153.58 (CH), 153.42 (C), 153.21 (C), 150.98 (CH), 148.31 (C), 148.14 (C), 141.86 (C), 138.46 (CH), 138.32 (CH), 137.23 (C), 136.47 (C), 135.19 (CH), 130.06 (CH), 129.56 (CH), 127.39 (CH), 127.21 (CH), 127.14 (CH), 126.46 (CH), 126.13 (CH), 125.19 (CH), 124.87 (CH), 124.67 (CH), 122.63 (CH), 121.93 (CH), 121.36 (CH), 20.48 (Me). Anal. Calcd for C32H25IN2O2Pd: C, 54.68; H, 3.59; N, 3.99. Found: C, 55.17; H, 3.42; N, 4.23.

Ortho-Palladated Phenol Derivatives [Pd{C(Ph)dC(Ph)C(Ph)dC(Ph)[C6H4OC(O)Me-2]}(OTf)(bpy)] (5). Diphenylacetylene (51 mg, 0.29 mmol) was added to a solution of 1b (50 mg, 0.097 mmol) in CH2Cl2 (10 mL). The solution was stirred for 5 min, TlOTf (34 mg, 0.097 mmol) was added, and the reaction mixture was stirred for 14 h. The suspension was filtered over Celite to give a clear yellow-brown filtrate. The filtrate was concentrated (ca. 3 mL) and Et2O was added, causing the precipitation of a solid, which was filtered, washed with Et2O (10 mL), and dried under an air stream to give pale yellow 5. Yield: 62 mg, 72%. Mp: 237 °C dec. IR (cm-1): ν(CO) 1772. 1H NMR (300 MHz, CDCl3): δ 8.79 (d, bpy, 1 H, 3JHH ) 4 Hz), 8.32 (d, bpy, 1 H, 3JHH ) 8 Hz), 8.148.09 (m, 2 H), 7.82 (dd, 1 H, 3JHH ) 8 Hz, 3JHH ) 8.5 Hz), 7.62 (dd, 1 H, 3JHH ) 5 Hz, 3JHH ) 6.5 Hz), 7.55-7.51 (m, 1 H), 7.35-7.11 (m, 10 H), 7.10-7.04 (m, 6 H), 7.00-6.85 (m, 3 H), 6.52 (d, 1 H, 3JHH ) 6.5 Hz), 6.35-6.24 (m, 2 H), 6.15 (dd, 1 H, 3 JHH ) 6.5 Hz, 3JHH ) 6.0 Hz), 5.36 (d, 1 H, 3JHH ) 5.0 Hz), 5.05 (dd, 1 H, 3JHH ) 4.5 Hz, 3JHH ) 4 Hz), 2.13 (s, Me, 3 H). 13 C{1H} NMR (50 MHz, CDCl3): δ 167.23 (CdO), 154.08 (C), 153.67 (C), 153.46 (C), 153.29 (CH), 153.08 (C), 148.54 (C), 148.13 (C), 147.29 (C), 141.40 (CH), 140.88 (CH), 140.68 (C), 140.44 (C), 139.30 (CH), 135.77 (C), 135.09 (C), 134.34 (C), 134.06 (C), 131.82 (C), 130.28 (CH), 129.97 (CH), 129.69 (CH), 129.63 (CH), 129.52 (CH), 129.40 (CH), 129.00 (CH), 128.11 (CH), 127.90 (CH), 127.82 (CH), 127.63 (CH), 127.57 (CH), 127.49 (CH), 127.14 (CH), 126.91 (CH), 126.18 (CH), 125.88 (CH), 124.20 (CH), 123.35 (CH), 122.57 (CH), 21.30 (Me). Anal. Calcd for C47H36F3N2O6SPd: C, 62.50; H, 3.91; N, 3.10; S, 3.55. Found: C, 62.33; H, 3.88; N, 3.22, S, 3.51. [Pd{η1(C):η2(C,C)-C8H12(C6H4OH-2)}(bpy)]TfO (6a). Complex 1a (100 mg, 0.21 mmol) was mixed with 1,5-cyclooctadiene (C8H12; 128 µL, 1.04 mmol) in CH2Cl2 (15 mL) under nitrogen. After a few minutes TlOTf (TfO ) CF3SO3, triflate; 73 mg, 0.21 mmol) was added and the resulting mixture was stirred for 14 h. The suspension was filtered over Celite (from this moment on the workup was carried out in air) and the filtrate concentrated (ca. 2 mL). Et2O (15 mL) was added and the resulting precipitate filtered, washed with Et2O (3 × 5 mL), and air-dried to give pale yellow 6a. Yield: 96 mg, 76%. Mp: 100-105 °C dec. IR (cm-1): ν(OH) 3372. 1H NMR (200 MHz, CDCl3): δ 8.36 (bd, bpy, 2 H, 3JHH ) 8 Hz), 8.2-8.0 (m, bpy, 4 H), 7.53 (bs, bpy and/or C6H4, 2 H), 7.12 (d, C6H4, 1 H, 3JHH ) 7 Hz), 7.08-6.9 (m, bpy and/or C6H4, 2 H), 6.67 (bt, C6H4, 1 H, 3JHH ) 7 Hz), 6.46 (m, CHdCH C8H12, 1 H), 6.10 (m, CHd CH C8H12, 1 H), 5.59 (bs, OH, 1 H), 3.09 (m, CH-Pd or CHC6H4, 1 H), 2.78 (m, CH-C6H4 or CH-Pd, 1 H), 2.7-2.2 (m, 4 × CH2 C8H12, 8 H). 13C{1H} NMR (75 MHz, (CD3)2CO): δ 148.95 (C), 143.81 (C), 136.21 (CH), 128.96 (C), 123.23 (CH), 123.02 (CH), 122.96 (CH), 119.76 (CH), 115.54 (CH), 112.09 (CH), 108.83 (CH), 105.41 (CH), 68.34 (CH, CH-C6H4 or CHPd), 46.14 (CH, CH-Pd or CH-C6H4), 41.80 (CH2), 38.89 (CH2), 27.19 (CH2), 25.66 (CH2). Anal. Calcd for C25H25F3N2O4PdS: C, 48.90; H, 4.27; N, 4.56; S, 5.22. Found: C, 48.82; H, 4.16; N, 4.41; S, 4.70. Single crystals were grown by liquid diffusion of Et2O into solutions of 6a in CH2Cl2. [Pd{η1(C):η2(C,C)-C8H12(C6H4OH-2)}(dtbbpy)]TfO (6a′). Pale orange 6a′ was similarly prepared from 1a′ (80 mg, 0.13 mmol), C8H12 (83 µL, 0.67 mmol), and TlOTf (48 mg, 0.13 mmol). Yield: 50 mg, 53%. Mp: 140 °C dec. IR (cm-1): ν(OH) 3328. 1H NMR (300 MHz, CDCl3, -40 °C): δ 8.23 (bs, dtbbpy, 1 H), 8.15 (d, dtbbpy, 1 H, 3JHH ) 6 Hz), 8.06 (s, H3 and H3′ dtbbpy, 2 H), 7.91 (bs, OH, 1 H), 7.69 (d, dtbbpy, 1 H, 3JHH ) 5 Hz), 7.27 (d, dtbbpy or C6H4, 1 H, 3JHH ) 5 Hz), 7.09 (t, dtbbpy and/or C6H4, 2 H, 3JHH ) 7 Hz), 6.99 (t, H4 or H5 C6H4, 1 H, 3JHH ) 7 Hz), 6.65-6.5 (m, C6H4 and CHdCH C8H12, 2 H), 6.29 (bm, CHdCH C8H12, 1 H), 2.96 (bs, CH-C6H4 or CHPd, 1 H), 2.64 (m, CH2, 2 H), 2.51 (m, CH2, 2 H), 2.23 (m, CH2, 2 H), 1.78 (bd, CH-Pd or CH-C6H4, 1 H, 3JHH ) 9 Hz), 1.42 (s, Me, 9 H), 1.41 (s, Me, 9 H) (at room temperature: 1.40 (s, Me, 18 H)). 13C{1H} NMR (75 MHz, CDCl3; only the most relevant signals): δ 69.16 (CH, CH-C6H4 or CH-Pd), 47.19

Organometallics, Vol. 23, No. 19, 2004 4419 (CH, CH-Pd or CH-C6H4), 41.33 (CH2), 37.58 (CH2), 35.65 (2 Me) 26.60 (CH2), 25.38 (CH2). FAB+ MS: m/z (% abundance) 576 (M+ - OTf, 41), 467 (M+ - TfO - C8H12, 10), 374 (Pd(dtbbpy)+, 30). HR FAB MS: calcd for C32H41N2OPd, m/z 573.225 915 (31), 574.229 270 (73), 575.225 364 (100), 576.228 719 (32), 577.225 783 (78), 578.229 138 (28), 579.227 058 (37), 580.230 413 (13); found, m/z 573.225 232 (27), 574.228 583 (69), 575.227 154 (100), 576.231 453 (32), 577.228 459 (78), 578.230 331 (31), 579.229 431 (37), 580.234 906 (15). Anal. Calcd for C33H41F3N2O4PdS: C, 54.66; H, 5.70; N, 3.86; S, 4.42. Found: C, 54.36; H, 5.89; N, 3.85; S, 4.41. Single crystals were grown by liquid diffusion of Et2O into solutions of 6a′ in CH2Cl2. Reaction of 1a with 2,5-Norbornadiene. Experiment A (1/5 Molar Ratio, Room Temperature). Complex 1a (81 mg, 0.17 mmol) was reacted with TlOTf (60 mg, 0.17 mmol) in acetone (10 mL) for 30 min. The suspension was filtered through Celite, giving a red solution. 2,5-Norbornadiene (86 µL, 0.85 mmol) was added to this solution and the mixture stirred for 24 h. A small amount of a precipitate was filtered off (8 mg) and the filtrate concentrated to dryness. The residue was triturated with Et2O (10 mL), giving a red solid, which was filtered and air-dried. Yield: 108 mg. FAB+ MS: m/z 1276 (M10+ ) [Pd{(C7H8)10C6H4OH-2}(bpy)]+ 0.2%), 1183 (M9+, 0.3%), 1092 (M8+, 0.5%), 1000 (M7+, 0.6%), 907 (M6+, 0.7%), 815 (M5+, 1%), 723 (M4+, 1%), 539 (M2+, 14%), 447 (M1+, 2%). Experiment B (1/5 Molar Ratio, Refluxing in Acetone). Complex 1a (100 mg, 0.21 mmol) and TlOTf (74 mg, 0.21 mmol) were mixed in acetone (10 mL) and reacted for 30 min. The suspension was filtered over Celite, 2,5-norbornadiene (107 µL, 1.05 mmol) was added to the filtrate, and the mixture was refluxed for 3 h. The suspension was cooled to room temperature and filtered, leaving an insoluble solid (32 mg). The filtrate was concentrated to dryness and the residue triturated with Et2O (10 mL), giving an orange solid, which was filtered, washed with Et2O, and dried. Yield: 116 mg. FAB+ MS: m/z 1276 (M10+, 0.13%), 1183 (M9+, 0.4%), 1092 (M8+, 0.6%), 1000 (M7+, 1%), 907 (M6+, 1%), 815 (M5+, 3%), 723 (M4+, 2%), 631 (M3+, 7%), 539 (M2+, 11%), 447 (M1+, 4%). Experiment C (1/5 Molar Ratio, 60 °C). Complex 1a (80 mg, 0.17 mmol), 2,5-norbornadiene (84 µL, 0.83 mmol), and TlOTf (59 mg, 0.17 mmol) were mixed in acetone (10 mL) and reacted in a Carius tube at 60 °C for 3.5 h. The mixture was filtered over Celite, the filtrate was concentrated to dryness, and the residue was triturated with Et2O (10 mL), giving an orange solid, which was filtered and air-dried. Yield: 96 mg. FAB+ MS: m/z 1276 (M10+ ) [Pd{(C7H8)10C6H4OH-2}(bpy)]+, 0.17%), 1183 (M9+, 0.3%), 1092 (M8+, 0.5%), 1000 (M7+, 0.9%), 907 (M6+, 0.8%), 815 (M5+, 2%), 723 (M4+, 2%), 631 (M3+, 7%), 539 (M2+, 13%), 447 (M1+, 2%). Experiment D (1/20 Molar Ratio, 60 °C). 1a (100 mg, 0.21 mmol), TlOTf (74 mg, 0.21 mmol), and 2,5-norbornadiene (427 µL, 4.2 mmol) were mixed in acetone (10 mL) and reacted in a Carius tube at 60 °C for 5 h. The mixture was filtered over Celite, the filtrate concentrated to dryness, and the residue triturated with Et2O (10 mL), giving an orange solid, which was filtered and air-dried. Yield: 133 mg. FAB+ MS: m/z 2013 (M18+ ) [Pd{(C7H8)18C6H4OH-2}(bpy)]+, 0.1%), 1921 (M17+, 0.1%), 1828 (M16+, 0.3%), 1736 (M15+, 0.3%), 1644 (M14+, 0.3%), 1552 (M13+, 0.3%), 1460 (M12+, 0.5%), 1367 (M11+, 0.7%), 1276 (M10+, 0.7%), 1183 (M9+, 1.6%), 1092 (M8+, 0.2%), 1000 (M7+, 0.6%), 907 (M6+, 1%), 815 (M5+, 0.6%), 723 (M4+, 0.3%), 631 (M3+, 0.4%), 539 (M2+, 0.9%), 447 (M1+, 1%). Reaction of 1a with Dicyclopentadiene (1/5 Molar Ratio, 60 °C). 1a (80 mg, 0.17 mmol) was reacted with dicyclopentadiene (115 µL, 0.85 mmol) and TlOTf in acetone (15 mL), in a Carius tube, at 60 °C for 3.5 h. The cooled mixture was filtered over Celite, the resulting solution concentrated (ca. 2 mL), and Et2O (10 mL) added. The precipitated solid was filtered, washed with Et2O (3 × 5 mL), and air-dried to give an orange solid. Yield: 67 mg. FAB+ MS: m/z (1016 (M5+

4420


) [Pd{(C10H12)5C6H4OH-2}(bpy)]+, 1%), 884 (M4+, 1.4%), 753 (M3+, 7%), 620 (M2+, 8%), 487 (M1+, 4%). Reaction of 1a with Norbornene (1/5 Molar Ratio, 60 °C). Complex 1a (80 mg, 0.17 mmol), norbornene (80 mg, 0.85 mmol), and TlOTf (59 mg, 0.17 mmol) were mixed in acetone (10 mL) and stirred at 60 °C for 3 h. After this time, the mixture was filtered over Celite, the resulting solution concentrated (2 mL), and Et2O (10 mL) added to precipitate an orange solid. The precipitated solid was filtered, washed with Et2O (3 × 5 mL), and air-dried. Yield: 78 mg. FAB+ MS: m/z 1391 (M11+ ) [Pd{(C7H10)11C6H4OH-2}(bpy)]+, 2%), 1297 (M10+, 2%), 1203 (M9+, 0.4%), 1108 (M8+, 15%), 1014 (M7+, 10%), 920 (M6+, 7%), 826 (M5+, 9%), 732 (M4+, 0.2%), 638 (M3+, 5%), 544 (M2+, 6%), 449 (M1+, 7%). Reaction of 2a with 2,5-Norbornadiene (1/4.5 Molar Ratio, Room Temperature). Complex 2a (54 mg, 0.11 mmol), 2,5-norbornadiene (51 µL, 0.50 mmol), and TlOTf (39 mg, 0.11 mmol) were mixed in CH2Cl2 (10 mL) and stirred for 20 h at room temperature. The suspension was filtered over Celite, the filtrate concentrated (2 mL), and Et2O added, precipitating a yellow solid, which was filtered, washed with Et2O (2 × 5 mL), and dried. Yield: 62 mg. FAB+ MS: m/z 1305 (M10+ ) [Pd{(C7H8)10C(O)C6H4OH-2}(bpy)]+, 0.8%), 1213 (M9+, 1%), 1121 (M8+, 4%), 1029 (M7+, 3%), 936 (M6+, 4%), 844 (M5+, 6%), 752 (M4+, 0.5%), 476 (M1+, 46%). Reaction of 2a with Norbornene (1/4.5 Molar Ratio, Refluxing in Acetone). Complex 2a (80 mg, 0.16 mmol), norbornene (68 mg, 0.72 mmol), and TlOTf (57 mg, 0.16 mmol) were mixed in acetone (10 mL), and the suspension was refluxed for 2.5 h and then filtered over Celite. Workup as described in the previous experiment renders a yellow solid. Yield: 62 mg. FAB+ MS: m/z 1325 (M10+ ) [Pd{(C7H10)10C(O)C6H4OH-2}(bpy)]+, 1%), 1231 (M9+, 0.8%), 1136 (M8+, 1%), 1042 (M7+, 1%), 948 (M6+, 1%), 854 (M5+, 1%), 760 (M4+, 0.8%), 666 (M3+, 4%), 572 (M2+, 5%), 477 (M1+, 37%). [Pd{C(dNXy)C(CO2Me)dC(CO2Me)(C6H4OH-2)}(bpy)]TfO (7aXy). XyNC (Xy ) 2,6-dimethylphenyl; 14 mg, 0,11 mmol) was added to a solution of 4a (69 mg, 0.11 mmol) in CH2Cl2 (20 mL) at 0 °C. The solution was stirred for a few minutes, and then TlOTf (39 mg, 0,11 mmol) was added. The reaction mixture was slowly warmed to room temperature and stirred for 6 h more and the resulting suspension filtered over Celite. The filtrate was concentrated (ca. 3 mL), and addition of Et2O (15 mL) formed a red-brown precipitate. The supernatant liquid phase was separated by a careful decantation from the precipitate and then concentrated to dryness to give a yellow solid. Recrystallization of this solid in CH2Cl2/nhexane gave the complex 7aXy as a yellow-orange powder. Yield: 62 mg, 72%. Mp: 237 °C dec. IR (cm-1): ν(OH) 3190 vb, 3402, ν(CdO) 1724, ν(CdN) 1620, 1586, 1574. 1H NMR (200 MHz, CDCl3): δ 11.95 (bs, OH, 1 H), 8.83 (d, bpy, 1 H, 3J 3 HH ) 5 Hz), 8.64 (d, bpy, 1 H, JHH ) 5 Hz), 8.40-8.36 (m, bpy, 2 H), 8.10 (dd, 1 H, 3JHH ) 8 Hz, 3JHH ) 8 Hz), 7.64-7.58 (m, 3 H), 7.31-7.15 (m, 6 H), 6.89-6.85 (m, 1 H), 3.97 (s, CO2Me, 3 H), 3.92 (s, CO2Me, 3 H), 2.26 (bs, 2 Me, 6 H). 13C{1H} NMR (50 MHz, CDCl3): δ 169.54 (CdN), 167.93 (CdO), 164.10 (CdO), 154.49 (C), 154.12 (C), 153.56 (C), 152.00 (CH), 151.17 (CH), 140.54 (CH), 140.22 (CH), 134.41 (C), 132.14 (C), 131.11 (C), 129.17 (CH), 128.85 (CH), 128.09 (CH), 127.54 (CH), 127.22 (CH), 123.29 (CH), 123.15 (CH), 122.78 (CH), 117.24 (CH), 53.76 (OMe), 53.09 (OMe), 18.47 (Me, Xy). Anal. Calcd for C32H28F3N3O8SPd: C, 49.40; H, 3.63; N, 5.40; S, 4.12. Found: C, 49.15; H, 3.58; N, 5.49, S, 4.13. Dimethyl 2-((2,6-Dimethylphenyl)imino)-2H-chromene3,4-dicarboxylate (8). Complex 4a (183 mg, 0.29 mmol) and XyNC (154 mg, 1.17 mmol) in CH2Cl2 (10 mL) were stirred for 1 h. The solvent was evaporated in vacuo, Et2O (10 mL) was added, and the suspension was filtered. The solid was washed with Et2O (2 × 5 mL) and dried in an air stream to give an orange solid (111 mg, see Discussion). The combined mother and washing liquors were concentrated to dryness, the

Vicente et al. residue was redissolved in CH2Cl2 (2 mL), and this solution was applied to a preparative TLC sheet with n-hexane/Et2O (1/2) as eluant. The yellow band was extracted with acetone (20 mL), the extract concentrated to dryness, and the residue dissolved in CH2Cl2 (20 mL). The solution was treated with anhydrous MgSO4 for 30 min and filtered, and the filtrate was concentrated (ca. 2 mL) and n-hexane (10 mL) added. The resulting suspension was filtered and the solid washed with n-hexane (10 mL) and air-dried to give yellow 8. Yield: 60 mg, 57%. Mp: 72 °C. IR (cm-1): ν(CO) 1732, 1652. 1H NMR (300 MHz, CDCl3): δ 7.70 (dd, 1 H, 3JHH ) 8 Hz, 4JHH ) 1 Hz), 7.4-7.3 (m, C6H4, 1 H), 7.2-7.1 (m, C6H4, 1 H), 7.04 (d, Xy, 2 H, 3JHH ) 7.5 Hz), 7.0-6.9 (m, C6H4 and Xy, 2 H), 3.98 (s, CO2Me, 3 H), 3.94 (s, CO2Me, 3 H), 2.13 (s, Me (Xy), 6 H). 13 C{1H} NMR (50 MHz, CDCl3): δ 164.77 (CdO), 164.07 (CdO), 153.00 (C), 144.51 (C), 143.65 (C), 135.03 (C), 134.35 (C), 133.00 (CH), 127.74 (C), 127.52 (CH), 126.83 (CH), 124.14 (CH), 123.41 (CH), 116.25 (CH), 115.28 (C), 53.08 (OMe), 52.91 (OMe), 18.16 (Me (Xy)). FAB+ MS: m/z (% abundance) 366 (MH+, 100), 365 (M+, 92). Anal. Calcd for C21H19NO5: C, 69.03; H, 5.24; N, 3.83. Found: C, 69.25; H, 5.43; N, 3.92. [Pd{CPhdCPh[C6H4OC(O)Me-2]}(CNXy)(bpy)]TfO (9b*Xy). XyNC (4 mg, 0.04 mmol) was added to a solution of complex 4b* (25 mg, 0.04 mmol) in CH2Cl2 (20 mL) at 0 °C. The color changed instantaneously from orange to pale yellow. After a few minutes of stirring, TlOTf (13 mg, 0,04 mmol) was added. The reaction mixture was slowly warmed to room temperature and stirred for 24 h to complete the formation of TlI. The reaction mixture was filtered over Celite to give a yellow filtrate, which was concentrated (ca. 3 mL). The addition of an excess of Et2O formed a yellow precipitate, which was filtered and dried in an air stream to give yellow 9b*Xy. Yield: 27 mg, 89%. Mp: 192 °C dec. IR (cm-1): ν(CtN) 2194, ν(CO) 1766. 1H NMR (200 MHz, CDCl3): δ 8.88 (d, bpy, 1 H, 3 JHH ) 5.5 Hz), 8.67 (dd, 2 H, 3JHH ) 7.5 Hz, 3JHH ) 8 Hz), 8.47 (d, bpy, 1 H, 3JHH ) 5.5 Hz), 8.26 (dd, 2 H, 3JHH ) 8 Hz, 3 JHH ) 10 Hz), 7.77 (dd, 1 H, 3JHH ) 7 Hz, 3JHH ) 7 Hz), 7.63 (m, 2 H), 7.48-6.92 (m, 5 H), 6.79 (dd, 1 H, 3JHH ) 8 Hz, 3JHH ) 7.5 Hz), 2.38 (s, Me, 6 H), 1.35 (s, OMe, 3H). 13C{1H} NMR (50 MHz, CDCl3): δ 167.65 (CdO), 156.18 (C), 153.67 (C), 150.75 (CH), 150.28 (CH), 147.83 (C), 143.50 (C), 142.0 (CH), 141.66 (CH), 140.77 (C), 140.24 (C), 137.57 (C), 135.63 (C), 135.52 (C), 132.70 (CH), 130.69 (CH), 129.85 (CH), 129.73 (CH), 128.81 (CH), 128.42 (CH), 128.37 (CH), 128.11 (CH), 127.96 (CH), 127.87 (CH), 126.76 (CH), 126.67 (CH), 125.49 (CH), 124.71 (CH), 123.76 (CH), 19.62 (OMe), 18.74 (Me). Anal. Calcd for C42H34F3N3O5SPd: C, 58.92; H, 4.00; N, 4.91; S, 3.75. Found: C, 58.27; H, 3.96; N, 4.91, S, 3.64. Some compounds containing the anion TfO, while spectroscopically pure and giving correct H, N, and S analyses, give a low percentage of C, despite many efforts to obtain a sample giving the appropriate value. The percentage found always corresponds to a formulation with one carbon less than the correct one. In this case, the calculated value for C41H34F3N3O5SPd is 58.33 (found 58.27), which agrees well with the experimental value. We believe that in such samples the conversion of the TfO carbon into CO2 does not take place. [Pd{K2C,N-(C7H8)C(dNtBu)(C6H4OH-2)}(bpy)]TfO (10at Bu). The complex 3atBu (120 mg, 0.21 mmol), 2,5-norbornadiene (97 µL, 0.95 mmol), and TlOTf (74 mg, 0.21 mmol) were mixed in CH2Cl2 (15 mL) and stirred for 4 h. The suspension was filtered over Celite, the filtrate was concentrated (ca. 2 mL), and Et2O (15 mL) was added. The resulting suspension was filtered and the solid washed with Et2O (2 × 3 mL) and dried to give yellow 10atBu. Yield: 115 mg, 82%. Mp: 136 °C. 1H NMR (300 MHz, CDCl3): δ 8.78 (br s, bpy, 2 H), 8.42 (d, bpy, 3JHH ) 8.15 Hz, 2 H), 8.21 (apparent t, bpy, 3JHH ) 7.5 Hz, 2 H), 7.72 (t, bpy, 3JHH ) 7.12 Hz, 2 H), 7.26-7.17 (m, C6H4, 2 H), 6.83 (s, C6H4, 2 H), 5.97 (s, CHdCH C7H8, 2 H), 2.95 (d, CH C7H8, 3JHH ) 6 Hz, 1 H), 2.66 (s, 2 × CH C7H8, 2 H), 2.49 (s, CH C7H8, 1 H), 2.32 (d, CH2 C7H8, 3JHH ) 8.7 Hz,

Ortho-Palladated Phenol Derivatives 1 H), 1.50-1.34 (bs, 3 × Me tBu and 1H CH2 C7H8, 10 H). At -55 °C the main difference is the splitting of the signal at 8.78 ppm into two doublets at 8.94 and 8.68 ppm. 13C NMR (300 MHz, CDCl3): δ 190.14 (C), 152.91 (2 × C), 149.95 (2 × CH), 140.14 (2 × CH), 136.14 (CH), 133.74 (CH), 131.15 (CH), 126.94 (2 × CH), 126.64 (CH), 124.96 (C), 123.89 (2 × CH), 118.48 (CH), 117.19 (CH), 62.48 (tBu), 60.26 (CH, C7H8), 55.08 (CH, C7H8), 49.64 (CH, C7H8), 46.31 (CH, C7H8), 45.71 (CH2, C7H8), 31.70 (Me). Single crystals were obtained by slow diffusion of Et2O into solutions of 10atBu in CH2Cl2 or acetone. Anal. Calcd for C29H30F3N3O4SPd: C, 51.21; H, 4.45; N, 6.18; S, 4.70. Found: C, 50.98; H, 4.30; N, 6.06, S, 4.85. [Pd{K2C,N-(C7H8)C(dNXy)[C6H4OC(O)Me-2]}(bpy)]TfO (10bXy). 2,5-Norbornadiene (16 mg, 0.18 mmol) was added to a solution of 3bXy (23 mg, 0.04 mmol) in CH2Cl2 (15 mL). After a few minutes, TlOTf (13 mg, 0.04 mmol) was added to the solution, and the resulting mixture was stirred for 14 h. The suspension was filtered over Celite, and the filtrate was concentrated (ca. 3 mL). Addition of Et2O gave a suspension that was centrifuged, washed with Et2O (2 × 5 mL), centrifuged again, and air-dried to give white 10bXy. Yield: 25 mg, 93%. Mp: 255 °C dec. IR (cm-1): ν(CO) 1736, ν(CdN) 1598. 1H NMR (200 MHz, CDCl ): δ 8.7-8.5 (m, 3 H), 8.35-8.27 3 (m, 1 H), 8.03 (dt, 1 H, 3JHH ) 8 Hz, 4JHH ) 1.5 Hz), 7.81-7.99 (m, 1 H), 7.42-6.91 (m, 8 H), 6.43-6.39 (m, C7H8 CHdCH, 1H), 6.13-6.09 (m, C7H8 CHdCH, 1H), 5.7-5.6 (m, H6 bpy cis to the imine group,29 1H), 3.48 (d, C7H8, 1 H, 3JHH ) 7 Hz), 3.13 (m, C7H8, 1 H), 2.90-2.84 (m, C7H8, 2 H), 2.74 (s, 1 H), 2.56, (s, C(O)Me, 3H), 2.36 (s, 3H, Me), 2.17 (s, 3H, Me), 1.65 (m, CH2, 1 H). 13C{1H} NMR: decomposition during the experiment. Anal. Calcd for C35H32F3N3O5SPd: C, 55.59; H, 4.19; N, 5.46; S, 4.16. Found: C, 55.41; H, 4.10; N, 5.38, S, 4.26. [Pd{K2C,N-(C10H12)C(dNXy)[C6H4OC(O)Me-2]}(bpy)]TfO (10b*Xy). This complex was similarly prepared from 3bXy (47 mg, 0.07 mmol), dicyclopentadiene (47 mg, 0.36 mmol), and TlOTf (25 mg, 0.07 mmol). The final suspension was filtered and the orange solid dried in an air stream. Yield: 38 mg, 66%. Mp: 291 °C dec. IR (cm-1): ν(CO) 1768, ν(CdN) 1600. 1H NMR (200 MHz, CDCl3): δ 8.62-8.48 (m, 3 H), 8.29 (t, 1 H, 3JHH ) 7.5 Hz), 8.01 (t, 1 H, 3JHH ) 7.5 Hz), 7.8-7.7 (m), 1 H, 7.4-6.8 (m, 8 H), 5.8 (m, 1 H, dicyclopentadiene), 5.6 (m, 1 H, dicyclopentadiene), 5.51 (m, H6, 1 H, bpy cis to the imine group),29 3.5-3.1 (m, 3 H, dicyclopentadiene), 2.62-2.00 (several m, 10 H, dicyclopentadiene and 2 Me (Xy)), 1.87 (s, 1 H, dicylopentadiene), 1.67 (d, 1 H, dicylopentadiene, 3JHH ) 8.8 Hz), 1.27 (m, 1 H, dicylopentadiene). 13C{1H} NMR: decomposition during the experiment. Anal. Calcd for C38H34F3N3O5SPd: C, 56.48; H, 4.24; N, 5.20; S, 3.97. Found: C, 56.77; H, 4.18; N, 5.19, S, 4.09. [Pd{K2C,N-(C7H8)C(dNXy)(C6H4CN-2)}(bpy)]TfO (10cXy). The complex 3cXy (100 mg, 0.17 mmol) and 2,5-norbornadiene (78 µL, 0.77 mmol) were mixed in CH2Cl2 (15 mL), and the resulting mixture was stirred for 5 min. TlOTf (60 mg, 0.17 mmol) was added, and the mixture was stirred for 6 h. The suspension was filtered over Celite and the resulting solution concentrated (ca. 2 mL). Addition of Et2O (15 mL) caused the precipitation of a solid, which was filtered, washed with Et2O (2 × 5 mL), and dried to give orange 10cXy. Yield: 103 mg, 82%. Mp: 218 °C dec. IR (cm-1): ν(CtN) 2224 (vw), ν(CdN) 1602. 1H NMR (300 MHz, CDCl3): δ 8.70-8.60 (m, 2 H), 8.53 (d, 1H, 3JHH ) 8.5 Hz), 8.32 (t, 1H, 3JHH ) 8 Hz), 8.05 (t, 1 H, 3J HH ) 8 Hz), 7.82-7.70 (m, 2 H), 7.60-7.50 (m, 2 H), 7.106.90 (several m, 5 H), 6.42 (m, C7H8, 1 H), 6.15 (m, C7H8, 1 H), 5.69 (d, 1 H, 3JHH ) 5.4 Hz), 3.40 (d, C7H8, 1 H, 3JHH ) 6 Hz), 3.15 (s, C7H8, 1 H), 2.91 (d, C7H8, 1 H, 3JHH ) 6 Hz), 2.69 (s, C7H8, 1 H), 2.58 (s, Me, 3 H), 2.28 (s, Me, 3 H), 2.24 (s, CH2, 1 H), 1.61 (d, CH2, 1 H, 3JHH ) 8.4 Hz). 13C{1H} NMR (75 MHz, CDCl3): δ 192.82 (C), 156.37 (C), 153.35 (C), 148.86 (CH), 146.86 (CH), 143.34 (C), 141.18 (CH), 140.44 (CH), 136.60 (C), 136.47 (CH), 134.15 (CH), 134.12 (CH), 132.79

Organometallics, Vol. 23, No. 19, 2004 4421 (CH), 131.91 (C), 130.98 (CH), 129.90 (C), 129.69 (CH), 129.08 (CH), 128.226 (CH), 127.30 (CH), 126.95 (CH), 126.26 (CH), 124.56 (CH), 123.69 (CH), 117.26 (C), 109.04 (C), 58.25 (CH, C7H8), 50.76 (CH, C7H8), 48.98 (CH, C7H8), 47.45 (CH, C7H8), 44.70 (CH2), 19.80 (Me), 18.32 (Me). Anal. Calcd for C34H29F3N4O3SPd: C, 55.41; H, 3.97; N, 7.60; S, 4.34. Found: C, 55.13; H, 4.28; N, 7.62, S, 4.29. cis-[Pd{K2C,N-{(C7H8)C(dNXy)(C6H4OH-2)}(CNXy)2]TfO (12aXy). 2,5-Norbornadiene (64 µL, 0.63 mmol) was added to a solution of 11aXy (100 mg, 0.14 mmol) in CH2Cl2 (15 mL) and the mixture stirred for 5 min. TlOTf (50 mg, 0.14 mmol) was added and the resulting mixture stirred for 17 h. The suspension was filtered over Celite, the yellow filtrate concentrated (ca. 2 mL), and Et2O (15 mL) added, causing the precipitation of a solid, which was filtered, washed with Et2O (2 × 3 mL), and dried to give 12aXy as a yellow solid. Yield: 84 mg, 72%. Mp: 102 °C. IR (cm-1): ν(OH) 3160 br, ν(CtN) 2178. 1H NMR (200 MHz, CDCl3): δ 9.08 (s, OH, 1 H), 7.56.5 (several m, 13 H), 6.11 (bs, CHdCH C7H8, 2 H), 3.90 (d, C7H8, 1 H, 3JHH ) 6 Hz), 3.25 (br s, C7H8, 1 H), 3.11 (dd, C7H8, 1 H, 3JHH ) 6 Hz, 4JHH ) 2 Hz), 2.77 (br s, C7H8, 1 H), 2.59 (s, Me, 3 H), 2.50 (s, 2 × Me, 6 H), 2.23 (s, Me, 3 H), 2.18 (m, C7H8, 2 H), 2.07 (s, 2 × Me, 6 H). 13C{1H} NMR (50 MHz, CDCl3): δ 159.31 (C), 154.27 (C), 150.81 (C), 150.35 (C), 147.97 (C), 142,57 (C), 142.04 (C), 135.77 (CH), 135.47 (CH), 135.06 (C), 131.99 (CH), 130.81 (CH), 130.47 (CH), 129.90 (C), 129.42 (C), 128.73 (CH), 128.60 (CH), 128.08 (CH), 127.67 (CH), 126.48 (CH), 126.15 (CH), 120.24 (C), 118.38 (CH, CHdCH C7H8), 117.70 (CH, CHdCH C7H8), 59.35 (CH C7H8), 49.87 (CH C7H8), 49.18 (CH C7H8), 47.63 (CH C7H8), 45.56 (CH2), 20.16 (Me), 18.73 (Me), 18.55 (Me), 18.29 (Me). Anal. Calcd for C41H40F3N3O4PdS: C, 59.03; H, 4.83; N, 5.04; S, 3.84. Found: C, 58.78; H, 5.14; N, 4.91, S, 3.54. Single crystals were grown by slow diffusion of Et2O into CH2Cl2 solutions of 12aXy. cis-[Pd{K2C,N-{(C7H10)C(dNXy)(C6H4OH-2)}(CNXy)2]TfO (12a*Xy). This complex was similarly prepared from 11aXy (140 mg, 0.19 mmol), norbornene (82 mg, 0.87 mmol), and TlOTf (69 mg, 0.19 mmol) as an orange solid. Yield: 105 mg, 68%. Mp: 160 °C. IR (cm-1): ν(OH) 3225 (v br), ν(CtN) 2168. 1H NMR (200 MHz, CDCl3): δ 9.12 (s, OH, 1 H), 7.46.5 (several m, 13 H), 4.18 (d, Pd-CHCHCN, 1 H, 3JHH ) 5 Hz), 3.52 (d, C7H10, Pd-CHCHCN, 1 H, 3JHH ) 5 Hz), 2.67 (s, Me, 3 H), 2.48 (s, Me, 6 H), 2.22 (s, Me, 3 H), 2.07 (s, Me, 6 H), 1.85-1.2 (several m, CH2, 6 H). 13C{1H} NMR (75 MHz, CDCl3): δ 154.35 (C), 147.67 (C), 135.60 (C), 135.15 (C), 132.01 (CH), 130.79 (CH), 130.49 (CH), 129.74 (C), 129.69 (C), 128.85 (CH), 128.64 (CH), 128.15 (CH), 127.55 (CH), 126.45 (CH), 126.24 (CH), 120.41 (C), 118.34 (CH), 117.78 (CH), 67.24 (CH C7H10), 57.59 (CH C7H10), 44.76 (CH C7H10), 42.77 (CH C7H10), 36.63 (CH2 C7H10), 30.29 (CH2 C7H10), 29.16 (CH2 C7H10), 20.25 (Me), 18.86 (2 × Me), 18.43 (2 × Me), 18.29 (Me). Anal. Calcd for C41H42F3N3O4PdS: C, 58.89; H, 5.06; N, 5.02; S, 3.83 Found: C, 58.65; H, 5.02; N, 5.09, S, 3.76. cis-[Pd{K2C,N-{(C7H8)C(dNXy)(C6H4CN-2)}(CNXy)2]TfO (12c′Xy). Orange 12c′Xy was similarly prepared from 11cXy (100 mg, 0.14 mmol), 2,5-norbornadiene (64 µL, 0.63 mmol), and TlOTf (50 mg, 0.14 mmol). Yield: 98 mg, 83%. Mp: 158 °C. IR (cm-1): ν(CtN) 2220, 2202. 1H NMR (400 MHz, CDCl3): δ 7.73 (d, 1H, 3JHH ) 7.3 Hz), 7.61-7.51 (m, 2H), 7.37 (t, 1H, 3JHH ) 7.7 Hz), 7.26-7.22 (m, 3H), 7.05 (d, 2H, 3JHH ) 7.7 Hz), 7.0 (d, 1H, 3JHH ) 7.0 Hz), 6.81-6.75 (m, 3H), 6.23-6.21 (m, 1H, C7H8), 6.14-6.11 (m, 1H, C7H8), 3.69 (d, 1H, C7H8, 3JHH ) 6.0 Hz), 3.37 (s, 1H, C7H8), 3.21 (dd, C7H8, 1H, 3JHH ) 6.06 Hz, 4JHH ) 2.2 Hz), 2.76 (s, 1H, C7H8), 2.73 (s, 3H, Me), 2.51 (s, Me, 6H), 2.27 (s, Me, 3H), 2.24 (s, CH2, 1H), 2.08 (s, Me, 6H), 1.73 (d, CH2, 1H, 3JHH ) 8.7 Hz). 13C{1H} NMR (100 MHz, CDCl3): δ 194.92 (C), 146.62 (C), 136.79 (CH), 136.09 (C), 135.63 (2 × C), 135.20 (2 × C), 134.78 (CH), 133.98 (CH), 133.50 (CH), 131.26 (CH), 131.08 (CH), 130.78 (CH), 130.27 (C), 128.91 (CH), 128.78 (CH), 128.69 (2 × CH), 128.23 (2 × CH), 127.78 (C), 127.62 (2 × CH), 117.32 (2 × C), 108.99

4422


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Table 1. Crystallographic Data for Complexes 2a′′, 4a′, 4b, and 6a formula Mr habit cryst size (mm) cryst syst space group cell constants a (Å) b (Å) c (Å) R (deg) β (deg) γ (deg) V (Å3) Z Dexptl (Mg m-3) µ (mm-1) F(000) T (°C) 2θmax, deg no. of rflns measd no. of indep rflns transmissn Rint no. of params no. of restraints Rw(F2, all rflns) R(F, >4σ(F)) S max ∆F (e Å-3)

2a′′

4a′‚Me2CO

4b

6a

C13H21IN2O2Pd 470.62 orange plate 0.38 × 0.10 × 0.02 orthorhombic Pna21

C33H41IN2O6Pd 794.98 yellow tablet 0.32 × 0.20 × 0.12 monoclinic P21/c

C24H21IN2O6Pd 666.73 yellow tablet 0.13 × 0.12 × 0.08 monoclinic P21/n

C13H21IN2O2Pd 612.93 pale yellow prism 0.38 × 0.10 × 0.02 monoclinic P21/c

16.668(3) 11.628(2) 8.163(2) 90 90 90 1582.2 4 1.976 3.12 912 -140 61 32 449 4844 0.52-0.94 0.107 178 1 0.120 0.046 1.05 2.6

10.6384(8) 11.5749(8) 28.797(2) 90 100.165(4) 90 3490.3 4 1.459 1.46 1600 -140 60 58 068 10193 0.75-0.86 0.027 402 108 0.128 0.043 1.03 2.6

10.8237(10) 16.5736(16) 13.7012(12) 90 106.618(3) 90 2355.2 4 1.880 2.14 1304 -130 60 27 790 6870 0.87-0.99 0.053 310 63 0.049 0.025 0.94 0.7

9.5008(11) 13.6806(14) 18.779(2) 90 102.305(4) 90 2384.7 4 1.707 0.93 1240 -140 60 34 456 6986 0.80-0.93 0.044 341 2 0.064 0.029 0.96 0.96

Table 2. Crystallographic Data for Complexes 6a′, 10atBu, 12aXy, and 12c′Xy formula Mr habit cryst size (mm) cryst syst space group cell constants a (Å) b (Å) c (Å) R (deg) β (deg) γ (deg) V (Å3) Z Dexptl (Mg m-3) µ (mm-1) F(000) T (°C) 2θmax, deg no. of rflns measd no. of indep rflns transmissn Rint no. of params no. of restraints Rw(F2, all rflns) R(F, >4σ(F)) S max ∆F (e Å-3)

6a′

10atBu

12aXy

12c′Xy

C33H41F3N2O4PdS 725.14 colorless lath 0.40 × 0.14 × 0.07 orthorhombic P212121

C29H30F3N3O4PdS 680.02 pale yellow lath 0.42 × 0.14 × 0.07 triclinic P1 h

C45H50F3N3O5PdS 908.34 colorless prism 0.39 × 0.15 × 0.15 tetragonal I41cd

C42H39F3N4O3PdS 843.23 colorless tablet 0.30 × 0.20 × 0.07 triclinic P1 h

11.7088(11) 12.1654(12) 23.021(2) 90 90 90 3279.1 4 1.469 0.69 1496 -140 56.6 60 634 8159 0.49-0.94 0.092 438 261 0.123 0.047 1.05 1.4

10.3850(12) 11.3773(12) 12.8852(14) 81.083(4) 74.117(4) 78.518(4) 1426.8 2 1.583 0.78 692 -140 60 30 132 8294 0.76-0.96 0.038 377 0 0.110 0.042 1.03 2.2

31.0575(14) 31.0575(14) 18.4842(12) 90 90 90 17829.3 16 1.354 0.52 7520 -140 56.6 127 542 11 066 0.80-0.93 0.068 563 212 0.087 0.035 0.98 0.6

9.7242(6) 11.7090(6) 19.0607(12) 99.618(4) 100.527(4) 108.472(4) 1964.0 2 1.426 0.58 864 -140 60 41 758 11 433 0.84-0.96 0.032 497 0 0.081 0.032 0.99 0.7

(C), 61.61 (CH; C7H8), 49.25 (CH; C7H8), 49.16 (CH; C7H8), 47.52 (CH; C7H8), 45.57 (CH2), 20.35 (Me, Xy), 18.73 (Me, Xy), 18.56 (Me, Xy), 18.28 (Me, Xy). Anal. Calcd for C42H39F3N4O3PdS: C, 59.82; H, 4.66; N, 6.64; S, 3.80. Found: C, 59.45; H, 4.98; N, 6.67, S, 3.66. Single crystals were grown by slow diffusion of n-pentane or n-hexane into CH2Cl2 solutions of 12c′Xy. X-ray Structure Determinations. Numerical details are presented in Tables 1 and 2. Data were recorded at low temperature on a Bruker SMART 1000 CCD diffractometer

using Mo KR radiation. Absorption corrections were based on multiple scans (program SADABS). Structures were refined anisotropically on F2 using the program SHELXL-97 (Prof. G. M. Sheldrick, University of Go¨ttingen). Hydrogen atoms of OH groups were refined freely and methyls as rigid methyl groups, a riding model was used for the other H atoms, except as stated below. Special features of refinement are as follows. 2a′′: absorption correction based on indexed faces; OH as rigid group; enantiomeric twin with Flack parameter 0.12(4). 4a′: acetone methyl H ill-defined. 6a: H at C1,C2 (coordinated

Ortho-Palladated Phenol Derivatives Scheme 1

Organometallics, Vol. 23, No. 19, 2004 4423 Scheme 2

double bond) and OH freely refined with SADI; H at C6 freely refined. 6a′: OH as rigid group; enantiomeric twin with Flack parameter 0.54(3); triflate disordered over two sites in ratio 4/1. 12aXy: OH as rigid group; triflate disordered over two sites in ratio 3/1; Flack parameter -0.03(2). 12c′Xy: H at C1 refined freely.

Results and Discussion Synthesis of Complexes cis-[Pd(C6H4OH-2)I(L2)] and Their Products of Monoinsertion of Carbon Monoxide and Isocyanides. By a method similar to the one we described for the synthesis of cis-[Pd(C6H4OX-2)I(bpy)] (X ) H (1a), MeC(O) (1b)),44 involving the reaction of 2-iodophenol with [Pd2(dba)3]‚dba and bpy, we have prepared the new derivatives cis-[Pd(C6H4OH2)I(L2)] (L2 ) 4,4′-di-tert-butyl-2,2′-bipyridine (dtbbpy) (1a′), N,N,N′,N′-tetramethylethylenediamine (tmeda) (1a"), 1,10-phenanthroline (phen) (1a′′′)) (Scheme 1). This procedure has proved to be useful for the synthesis of similar organopalladium complexes.18,55 We have observed that the yields are better if the molar ratios of 2-iodophenol to Pd and L2 to Pd are 2/1 or even greater. However, as some decomposition to palladium metal always occurs, only moderate to low yields were obtained (33-54%). The acyl derivatives [Pd{C(O)C6H4OH-2}I(L2)] (L2 ) dtbbpy (2a′), tmeda (2a′′)) were obtained when CO was bubbled through a CH2Cl2 solution of 1a′ or 1a′′. Similarly, 1a′ reacts with isonitriles RNC (1/1 molar ratio) to give the monoinserted species [Pd{C(dNR)C6H4OH-2)}I(dtbbpy)] (R ) Xy (3a′Xy), tBu (3a′tBu)) (Scheme 1).44 In a similar reaction of 1a′′ with CNXy or tBuNC a complex mixture, which could not be separated, was obtained. Insertion of Alkynes. Complex 1a, 1a′, or 1b reacts with an excess of MeO2CCtCCO2Me (1/(4.5-4.8) molar ratio) to give the vinylpalladium complex [Pd{C(CO2Me)dC(CO2Me)(C6H4OX-2)}I(L2)] (X ) H, L2 ) bpy (4a), dtbbpy (4a′); X ) C(O)Me, L2 ) bpy (4b)) (Scheme 2), which is the result of the monoinsertion of the alkyne (55) van Asselt, R.; Vrieze, K.; Elsevier, C. J. J. Organomet. Chem. 1994, 480, 27. Markies, B. A.; Canty, A. J.; Degraaf, W.; Boersma, J.; Janssen, M. D.; Hogerheide, M. P.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J. Organomet. Chem. 1994, 482, 191.

Chart 1

into the Pd-C bond. Similarly, 1b reacts with PhCt CPh (1/5.2 molar ratio) to give [Pd{CPhdCPh[C6H4OC(O)Me-2]}I(bpy)] (4b*). The structures proposed for these complexes have been confirmed by X-ray diffraction methods for complexes 4a′ and 4b (see below). Monoinsertions of alkynes have been reported starting from haloaryl complexes17,23,24,56 or after removing the halogen ligand.21 Complex 1b reacts with PhCtCPh and TlOTf (1/3/1 ratio) to give a precipitate of TlI and a compound whose analytical and spectroscopic data indicate that a double alkyne insertion has taken place, forming a butadienylpalladium derivative, [Pd{CPhdCPhCPhdCPh[C6H4OC(O)Me-2]}(OTf)(bpy)] (5). Complexes resulting after the insertion of two alkynes into Pd-C bonds are known, and their structures show a trans/cis-butadiene1,4-diyl group linking the previously palladated carbon and the palladium atom (see Chart 1, showing one of our previously reported complexes)21 and the coordination of the same heteroatom of the ortho substituent previously coordinated.16,20,21,25 In one case in which such a substituent had a heteroatom with a low tendency to coordinate to the palladium atom, in trans-[Pd{C6H(OMe)3-2,3,4-CH2OEt-6}Cl(py)2], the reaction with MeO2CCtCCO2Me and TlOTf gave the complex trans(56) Gu¨l, N.; Nelson, J. H.; Willis, A. C.; Rae, A. D. Organometallics 2002, 21, 2041.

4424

Organometallics, Vol. 23, No. 19, 2004 Scheme 3

[Pd{cis,cis-C(CO2Me)dC(CO2Me)C(CO2Me)dC(CO2Me)C6H(OMe)3-2,3,4-CH2OEt-6}(OTf)(py)2],21 in which 1-arylcis/cis-butadien-4-yl and triflato ligands are coordinated to the Pd atom. Given the similarity, we propose for complex 5 the formation of a cis/cis-butadiene-1,4-diyl arrangement (Scheme 2). However, we have not been able to grow single crystals of 5 in order to confirm its structure, and other possibilities cannot be discounted. The same type of cis,cis insertion occurs when the ortho substituent does not have a heteroatom to coordinate to palladium.24 Complex 1a′ reacts with PhCtCPh in the presence of TlOTf to give a mixture which does not seem to contain any alkyne-inserted product. No reaction occurs if TlOTf is not used. The compound 1a′′ reacts with MeO2CCtCCO2Me, with or without TlOTf, to give mixtures that we could not resolve. The reaction with PhCtCPh and TlOTf gives also complex mixtures; without TlOTf there is no reaction. Insertion of Alkenes. Complexes 1a and 1a′ react with TlOTf and an excess of 1,5-cyclooctadiene (C8H12) to give [Pd{η1(C):η2(C,C)-C8H12(C6H4OH-2)}(bpy)]TfO (6a) and [Pd{η1-(C):η2(C,C)-C8H12(C6H4OH-2)}(dtbbpy)]TfO (6a′), respectively (Scheme 3), resulting from the insertion of one of the two CdC bonds of the cyclooctadiene into the aryl-palladium bond and the coordination of the remaining one, as confirmed by X-ray studies (see below). The aryl group is at the endo position, in accordance with the fact that it was previously bonded to the metal center.57,58 Reactions of palladium diene complexes with nucleophiles such as hydroxide, alkoxides, carboxylate, malonate, azide, and amines take place by direct exo attack at the coordinated CdC.58,59 The reaction of 1a with TlOTf gives rise to the precipitation of TlI and the formation of solutions which must contain [Pd(C6H4OH-2)(OTf)(bpy)], [Pd(C6H4OH2)(S)(bpy)]TfO (S ) coordinated solvent), or [Pd(κ2C,OC6H4OH-2)(bpy)]TfO. When these solutions are reacted (57) Segnitz, A.; Kelly, E.; Taylor, S. H.; Maitlis, P. M. J. Organomet. Chem. 1977, 124, 113. Albeńiz, A. C.; Espinet, P.; Jeannin, Y.; PhilocheLevisalles, M.; Mann, B. E. J. Am. Chem. Soc. 1990, 112, 6594. (58) Hoel, G. R.; Stockland, R. A.; Anderson, G. K.; Ladipo, F. T.; Braddockwilking, J.; Rath, N. P.; Marequerivas, J. C. Organometallics 1998, 17, 1155.

Vicente et al. Scheme 4

with 2,5-norbornadiene, dicyclopentadiene, or norbornene under various conditions (Pd/olefin ratio of 1/5 or 1/20, room temperature, or refluxing acetone; see Experimental Section), it is possible to isolate a small amount of an insoluble material and a mixture of soluble polymeric complexes (Scheme 4). The study of these solids by FAB+ MS indicates the presence of the polyinserted species [Pd(C7H8)n(C6H4OH-2)(OTf)(bpy)] (n ) 1-18), [Pd(C10H12)n(C6H4OH-2)(OTf)(bpy)] (n ) 1-5), or [Pd(C7H10)n(C6H4OH-2)(OTf)(bpy)] (n ) 1-11), respectively. These results are related to those recently published by Liu and co-workers, who have described several reactions of cationic iminephosphinemethylpalladium complexes with olefins.60 The result of these reactions do not seem to be dependent on the temperature (compare experiments A and B of the reaction (59) Stille, J. K.; James, D. E. J. Organomet. Chem. 1976, 108, 401. Rotondo, E.; Cusmano-Priolo, F.; Donato, A.; Pietropaolo, R. J. Organomet. Chem. 1983, 251, 273. Stille, J. K.; Morgan, R. A.; Whitehurst, D. D.; Doyle, J. R. J. Am. Chem. Soc. 1965, 87, 3282. Schultz, R. G. J. Organomet. Chem. 1966, 6, 435. Pietropaolo, R.; Cusmano-Priolo, F.; Rotondo, E.; Spadaro, A. J. Organomet. Chem. 1978, 155, 117. Anderson, C. B.; Burreson, B. J. J. Organomet. Chem. 1967, 7, 181. Akbarzadeh, M.; Anderson, C. B. J. Organomet. Chem. 1980, 197, C5. Tsuji, J.; Takahashi, H. J. Am. Chem. Soc. 1965, 87, 3275. Tada, M.; Kuroda, Y.; Sato, T. Tetrahedron Lett. 1969, 2871. Palumbo, R.; De Renzi, A.; Panunzi, A.; Paiaro, G. J. Am. Chem. Soc. 1969, 91, 3874. Evans, D. J.; Kane-Maguire, L. A. P. J. Organomet. Chem. 1986, 312, C24. (60) Chen, Y. C.; Chen, C. L.; Chen, J. T.; Liu, S. T. Organometallics 2001, 20, 1285.


with 2,5-norbornadiene in the Experimental Section). However, a greater olefin to Pd ratio leads to products giving peaks corresponding to higher values of n (compare experiments C and D of the reaction with norbornadiene). We have attempted a palladium-catalyzed polymerization of 2,5-norbornadiene, but the reaction of 1a, TlOTf, and 2,5-norbornadiene (1:1:650 molar ratio) gives after 24 h most of the alkene and a small amount of an intractable yellow solid which, after treatment with aqueous HCl, transforms into an almost white solid also impossible to study because of its insolubility. We have also studied the reactivity of the CO-inserted complex 2a with 2,5-norbornadiene and norbornene, and the results are similar, since a mixture of polyinserted species can be detected by FAB MS. In the first case, the reaction was carried out at room temperature (see Experimental Section) and the species [Pd{(C7H8)nC(O)C6H4OH-2}(bpy)]+ (n ) 1, 4-10) can be observed. With norbornene, the reaction at room temperature gives a mixture whose FAB MS spectrum does not indicate the presence of similar cations; however, if the reaction is performed in refluxing acetone, the FAB spectrum of the resulting mixture gives peaks corresponding to [Pd{(C7H8)nC(O)C6H4OH-2}(bpy)]+ (n ) 1-10). Alkyne/Isonitrile Sequential Insertion Reactions. The reaction of 4a with XyNC in the presence of TlOTf (1/1/1 molar ratio) results in the insertion of the isonitrile into the alkenyl carbon-palladium bond to give [Pd{C(dNXy)C(CO2Me)dC(CO2Me)(C6H4OH-2)}(bpy)]TfO (7aXy) (Scheme 5). We tentatively propose a structure for 7aXy in which one of the carboxylate groups is bonded to Pd, because some products of the insertion of MeO2CCtCCO2Me into the Pd-C bond have this structure.23,61 However, coordination of the TfO anion cannot be discounted. To the best of our knowledge, only two examples of sequential insertion of an alkyne and an isocyanide into a Pd-C bond are known. In both cases, an intramolecular insertion of alkyne into an iminoacyl carbon-palladium bond took place.28,31 In our case, the order of the insertion was the opposite: we first inserted the alkyne into the arylpalladium bond and then the isocyanide. When the same reaction is carried out in the absence of TlOTf an illdefined solid could be isolated; however, when an excess of XyNC (4-fold) is used, after workup, an orange solid precipitates in Et2O; we have not been able to determine the nature of this solid, but it very probably contains palladium in the form of one or more palladium(I) isocyanide complexes. The iminecoumarin dimethyl 2-((2,6-dimethylphenyl)imino)-2H-chromene-3,4-dicarboxylate (8) could be isolated from the mother liquors; its analytical and spectroscopic data are in agreement with the proposed formulation (Scheme 5). This reaction constitutes the first example of a palladium-mediated formation of an organic product, resulting from the sequential insertion of an alkyne and an isonitrile into a Pd-C bond. It may proceed through the insertion of the isonitrile into the alkenyl-palladium bond of 4a, giving an intermediate such as [Pd{C(dNXy)C(CO2(61) Vicente, J.; Saura-Llamas, I.; Ramı´rez de Arellano, M. C. J. Chem. Soc., Dalton Trans. 1995, 2529. Vicente, J.; Saura-Llamas, I.; Palin, M. G.; Jones, P. G. J. Chem. Soc., Dalton Trans. 1995, 2535.

Organometallics, Vol. 23, No. 19, 2004 4425 Scheme 5

Me)dC(CO2Me)(C6H4OH-2)}I(bpy)], which may decompose to 8, HI, and “Pd0(bpy)”. The latter, in the presence of unreacted isocyanide, would give the components of the orange solid previously mentioned. Using a 2-fold excess the reaction gives a complex mixture. Similar reactions from 4a′ give mixtures containing mainly a compound which could, in accordance with its 1H NMR spectrum, be the Pd(I) complex [Pd2I2(CNXy)4].62 The reaction of 4b* with XyNC and TlOTf (1:1:1) gives the isonitrile-coordinated complex [Pd{CPhdCPh[C6H4OC(O)Me-2]}(CNXy)(bpy)]TfO (9b*Xy) (Scheme 5). The diinserted complex 5 reacts with CNXy to give complex mixtures. Isonitrile/Alkene Sequential Insertions. The iminoacyl complexes [Pd{C(dNtBu)(C6H4OH-2)}I(bpy)] (3atBu), [Pd{C(dNXy)(C6H4OC(O)Me-2)}I(bpy)] (3bXy), and [Pd{C(dNXy)(C6H4CN-2)}I(bpy)] (3cXy) react with 2,5-norbornadiene (C7H8) or dicyclopentadiene (C10H12) in the presence of TlOTf, giving a precipitate of TlI and solutions from which the isocyanide/alkene coinserted complexes [Pd{κ2C,N-(C7H8)C(dNtBu)(C6H4OH-2)}(bpy)]TfO (10atBu), [Pd{κ2C,N-(C7H8)C(dNXy)[C6H4OC(O)Me-2]}(bpy)]TfO (10bXy), and [Pd{κ2C,N-(C10H12)C(dNXy)[C6H4OC(O)Me-2]}(bpy)]TfO (10b*Xy), respectively, can be isolated (Scheme 6). The synthesis of the complex analogous to 10atBu but with XyNC was also attempted, but a mixture was obtained. Similar reactions of 11aXy with TlOTf and 2,5-norbornadiene or (62) Vicente, J.; Abad, J. A.; Martıńez-Viviente, E.; Jones, P. G. Organometallics 2002, 21, 4454.

4426

Organometallics, Vol. 23, No. 19, 2004 Scheme 6

norbornene or of 11cXy with TlOTf and 2,5-norbornadiene gave the coinserted species cis-[Pd{κ2C,N-(C7H8)(12aXy), cisC(dNXy)(C6H4OH-2)}(CNXy)2]TfO [Pd{κ2C,N-(C7H10)C(dNXy)(C6H4OH-2)}(CNXy)2]TfO (12a*Xy) and cis-[Pd{κ2C,N-(C7H8)C(dNXy)(C6H4CN2)}(CNXy)2]TfO (12c′Xy), respectively. There is only one previous report of the successive insertion of isocyanides and alkenes into Pd-C bonds29 involving methylpalladium complexes. Ours are the first examples of sequencial insertion of isonitriles and alkenes into arylpalladium bonds. We propose, for all the derivatives of norbornadiene (10atBu, 10bXy, 10cXy, 12aXy, 12c′Xy) and norbornene (12aXy), structures resulting from an exo insertion of the olefins, because this is confirmed by the X-ray crystal structure of 10atBu, 12aXy, and 12c′Xy (see below) and is the general mode of insertion into C-Pd bonds.10,14,29,63 Spectroscopic Properties. The band assignable to ν(OH) in the IR spectra of the ortho-palladated phenol complexes (those containing the letter a) is observed within the range 3500-3150 cm-1. In the case of 1a′ two bands at 3444 and 3402 cm-1 are observed; this may be due to the existence of two different structural environments of the OH group in the solid state. In contrast, the analogous 1a′′ and 1a′′′ show only one band at 3442 and 3402 cm-1, respectively, as expected. It is not possible to observe clearly the corresponding bands in complexes 2a′, 2a′′, 3a′Xy, 3a′tBu, 4a, and 10atBu. (63) Catellani, M.; Motti, E.; Paterlini, L. J. Organomet. Chem. 2000, 594, 240. Brumbaugh, J. S.; Whittle, R. R.; Parvez, M.; Sen, A. Organometallics 1990, 9, 1735. Li, C. S.; Cheng, C. H.; Liao, F. L.; Wang, S. L. J. Chem. Soc., Chem. Commun. 1991, 710.

Vicente et al.

Complexes having the ortho substituent C(O)Me or OC(O)Me show the ν(CdO) band in the region 1702-1772 cm-1, while those having CO2Me groups show one or two bands in the region at 1692-1614 cm-1. In the case of the complex 7aXy, its IR spectrum shows one band at 1724 cm-1 assignable to ν(CO2) and three bands at 1620, 1586, and 1574 cm-1; one of them may be due to the ν(CdN) group, and one of the remaining may be assignable to the ν(CdO) mode corresponding to the carboxylate group coordinated to the palladium atom (Scheme 5). The 1H NMR signal corresponding to the OH group appears in the region 5.59-5.83 ppm for 1a,44 1a′, 1a′′, and 6a. The other ortho-palladated phenol complexes show the resonance for the OH proton at higher chemical shifts: 6.28 (4a′), 6.35 (4a), 7.91 (6a′), 9.08 (12aXy), 9.12 (12a*Xy), 11.10 (2a′′), 11.25 (2a′), 11.95 (7aXy), and 14.68 (3a′Xy) ppm. This may be associated with the deshielding caused by a hydrogen bond in solution involving the OH group. In complexes 2a′, 2a′′, 3a′Xy, and 7aXy, such a bond is probably intramolecular, with a carbonyl oxygen or an imine nitrogen acting as acceptor; this is in accordance with the solid-state structure of 2a′′ (see below) and with the spectroscopic properties of similar complexes.44 In complexes 4a′, 6a′, 12aXy, and 12a*Xy the hydrogen bond could have the form OH‚‚‚OTf. In fact, in the crystal structures of 12aXy and 6a′ it is shown that the OH group makes a hydrogen bond to an oxygen atom of the triflate anion (see below). However, it is difficult to explain that the OH proton in 6a′ appears at higher chemical shift than that in 6a if both show an OH‚‚‚OTf hydrogen bond. In 3a′tBu and 10atBu the resonance due to the OH proton was not found. The NMR spectra of complexes 1a′ and 2a′′ show that they slowly decompose in solution to the corresponding complexes [PdI2L2] (see Experimental Section). The compounds 6a′ and 10atBu show fluxional behavior because the halves of dtbbpy and bpy, respectively, are equivalent at room temperature. However, at low temperature (-40 and -55 °C), the fluxional processes are slower than the NMR time scale, showing the two different parts of those ligands. Such behavior has been observed previously, and it has been proposed that the rotation takes place through the dissociation of one Pd-N ligand, probably that trans to the carbon donor ligand, which exerts a greater trans influence, to give a Y-shaped intermediate.64 Dicyclopentadiene has two insertion possibilities, involving the norbornene or the cyclopentadiene ring. We tentatively propose the former in 10b*Xy, as it is the preferred mode of insertion of C10H12 into an acylpalladium complex, giving [Pd{C10H12C(O)Me}(bpy)]+.14,65 The 1H and 13C NMR spectra of this complex show duplicated signals associated with the two possible isomers, which differ in the position of the noninserted double bond of the cyclopentene moiety. In our case, the 1H spectrum of 10b*Xy shows also duplicated signals (by comparison with the spectrum of 10bXy) and we tentatively formulate 10b*Xy as an exo-inserted com(64) Delis, J. G. P.; Aubel, P. G.; Vrieze, K.; van Leeuwen, P.; Veldman, N.; Spek, A. L.; van Neer, F. J. R. Organometallics 1997, 16, 2948. (65) Markies, B. A.; Rietveld, M. H. P.; Boersma, J.; Spek, A. L.; van Koten, G. J. Organomet. Chem. 1992, 424, C12.


Figure 1. Ellipsoid representation of 2a′′ (50% probability). Selected bond lengths (Å) and angles (deg): PdC(7) ) 1.987(8), Pd-N(2) ) 2.130(6), Pd-N(1) ) 2.211(5), Pd-I 2.5945(8), O(1)-C(2) ) 1.337(8), O(2)-C(7) ) 1.119(9); C(7)-Pd-N(2) ) 91.2(2), N(2)-Pd-N(1) ) 83.72(19), C(7)-Pd-I ) 88.1(2), N(1)-Pd-I ) 97.32(14), O(2)-C(7)-C(1) ) 121.4(7), O(2)-C(7)-Pd ) 123.3(5), C(1)-C(7)-Pd ) 114.7(5).


Figure 3. Ellipsoid representation of 4b (50% probability). Selected bond lengths (Å) and angles (deg): Pd-C(1) ) 1.9804(19), Pd-N(22) ) 2.0686(16), Pd-N(32) ) 2.1071(16), Pd-I ) 2.5930(3), O(1)-C(2) ) 1.204(2), O(2)C(2) ) 1.348(2), O(2)-C(3) ) 1.446(3), O(3)-C(5) ) 1.210(2), O(4)-C(5) ) 1.338(2), O(4)-C(6) ) 1.441(3), O(5)-C(7) ) 1.373(2), O(5)-C(12) ) 1.410(2), O(6)-C(7) ) 1.198(3), C(1)-C(4) ) 1.348(3); C(1)-Pd-N(22) ) 92.65(7), N(22)-Pd-N(32) ) 79.07(6), C(1)-Pd-I ) 88.43(6), N(32)-Pd-I ) 99.92(5), C(4)-C(1)-C(2) ) 120.59(18), C(4)-C(1)-Pd ) 125.56(15), C(2)-C(1)-Pd ) 112.93(14), O(1)-C(2)-O(2) ) 122.33(19), O(1)-C(2)-C(1) ) 124.04(19), O(2)-C(2)-C(1) ) 113.62(17), C(1)-C(4)C(11) ) 125.27(17), C(1)-C(4)-C(5) ) 120.61(18), C(11)C(4)-C(5) ) 114.08(16), O(3)-C(5)-O(4) ) 124.39(18), O(3)-C(5)-C(4) ) 123.69(18), O(4)-C(5)-C(4) ) 111.92(16), O(6)-C(7)-O(5) ) 122.5(2), O(6)-C(7)-C(8) ) 126.9(2), O(5)-C(7)-C(8) ) 110.58(19).

Figure 2. Ellipsoid representation of 4a′‚Me2CO (50% probability). Selected bond lengths (Å) and angles (deg): Pd-C(10) ) 2.001(3), Pd-N(21) ) 2.073(3), Pd-N(31) ) 2.098(3), Pd-I ) 2.5692(4), O(1)-C(2) ) 1.366(4), O(2)C(8) ) 1.206(4), O(3)-C(8) ) 1.340(4), O(3)-C(9) ) 1.444(4), O(4)-C(11) ) 1.204(4), O(5)-C(11) ) 1.346(4), C(98)-O(99) ) 1.190(6); C(10)-Pd-N(21) ) 98.04(11), N(21)-Pd-N(31) ) 78.42(10), C(10)-Pd-I ) 86.89(9), N(31)-Pd-I ) 96.74(7), C(10)-C(7)-C(1) ) 121.8(3), C(10)-C(7)-C(8) ) 122.5(3), C(1)-C(7)-C(8) ) 115.6(3), C(7)-C(10)-C(11) ) 121.5(3), C(7)-C(10)-Pd ) 124.7(2), C(11)-C(10)-Pd ) 113.8(2).

Figure 4. Ellipsoid representation of 6a (30% probability). Selected bond lengths (Å) and angles (deg): Pd-C(6) ) 2.0306(18), Pd-N(31) ) 2.1126(15), Pd-N(21) ) 2.1575(16), Pd-C(1) ) 2.1788(19), Pd-C(2) ) 2.183(2), C(1)-C(2) ) 1.382(3); C(6)-Pd-N(31) ) 98.04(7), N(31)Pd-N(21) ) 77.87(6), C(6)-Pd-C(1) ) 81.02(8), C(6)-PdC(2) ) 89.25(8), N(21)-Pd-C(2) ) 98.21(7), C(1)-Pd-C(2) ) 36.96(8).

plex involving the norbornene moiety, as observed previously;14 however, the complexity of such a spectrum and the absence of 13C NMR data prevent us from confirming these features unambiguously. The NMR spectra of complexes 10Xy show that both methyl groups of the Xy substituent are inequivalent, due probably to a restricted rotation around the C-N bond at room temperature. Something similar seems to occur in complexes 12, since they show four signals assignable to methyl groups, which implies that one of the Xy groups has a restricted rotation; we believe that it must be also the iminic Xy group. The 13C spectra of 12aXy and 12c′Xy confirm the presence of inserted norborna-

diene (four alkyl CH, two olefinic CH, and one CH2) and norbornene in 12a*Xy (four alkyl CH and three CH2 signals). X-ray Crystal Structures of Complexes 2a′′, 4a′, 4b, 6a, 6a′, 10atBu, 12aXy, and 12c′Xy. All structures show a distorted-square-planar geometry around the palladium atom (Figures 1-8). The main distortion is associated with the small bite angle of the chelating ligand (N-Pd-N (deg): 2a′′, 83.72(19); 4a′, 78.42(10); 4b, 79.07(6); 6a, 77.87(6); 6a′, 78.31(13); 10atBu, 75.65(8); N-Pd-C (deg): 12aXy, 83.20(12); 12c′Xy, 83.02(6)). The Pd-I distances in 2a′′ and 4b are not significantly different (2a′′, 2.5945(8) Å; 4b, 2.5930(3) Å), as expected for the similar trans influences of the N-donor ligands tmeda and bpy. However, 4a′ shows a

4428 Organometallics, Vol. 23, No. 19, 2004

Figure 5. Ellipsoid representation of 6a′ (30% probability). The anion is omitted. Selected bond lengths (Å) and angles (deg): Pd-C(1) ) 2.041(4), Pd-N(31) ) 2.082(3), Pd-N(21) ) 2.162(3), Pd-C(5) ) 2.199(5), Pd-C(4) ) 2.214(5), C(4)C(5) ) 1.353(9); C(1)-Pd-N(31) ) 97.02(16), N(31)-PdN(21) ) 78.31(13), C(1)-Pd-C(5) ) 87.91(19), N(21)-PdC(5) ) 98.89(17), C(1)-Pd-C(4) ) 80.96(19), N(31)-PdC(4) ) 167.58(19), N(21)-Pd-C(4) ) 102.22(17), C(5)-PdC(4) ) 35.7(2).

Figure 6. Ellipsoid representation of 10atBu (50% probability). The anion is omitted. Selected bond lengths (Å) and angles (deg): Pd-C(1) ) 2.008(2), Pd-N(41) ) 2.074(2), Pd-N(1) ) 2.0934(19), Pd-N(31) ) 2.322(2), N(1)-C(8) ) 1.287(3), N(1)-C(9) ) 1.511(3), C(4)-C(5) ) 1.328(4); C(1)-Pd-N(41) ) 92.23(9), C(1)-Pd-N(1) ) 81.47(8), N(41)-Pd-N(31) ) 75.65(8), N(1)-Pd-N(31) ) 111.80(8), C(8)-N(1)-C(9) ) 123.53(19), C(8)-N(1)-Pd ) 116.11(16), C(9)-N(1)-Pd ) 120.36(15), N(1)-C(8)-C(21) ) 127.0(2), N(1)-C(8)-C(2) ) 117.6(2), C(21)-C(8)-C(2) ) 115.4(2).

slightly shorter Pd-I length (2.5692(4) Å) that cannot be attributed to a smaller trans influence of the dtbbpy ligand. The Pd-N distances trans to the C-donor ligands in complexes 2a′′ (2.211(5) Å), 4a′ (2.098(3) Å), and 4b (2.1071(16) Å) are longer than those trans to I

Vicente et al.

Figure 7. Ellipsoid representation of 12aXy (30% probability). The anion is omitted. Selected bond lengths (Å) and angles (deg): Pd-C(40) ) 1.933(3), Pd-C(2) ) 2.034(3), Pd-N(2) ) 2.049(2), Pd-C(30) ) 2.072(4), N(2)C(20) ) 1.276(4), N(2)-C(21) ) 1.444(4), N(3)-C(30) ) 1.141(4), N(3)-C(31) ) 1.408(4), N(4)-C(40) ) 1.146(4), N(4)-C(41) ) 1.397(4), C(5)-C(6) ) 1.313(5); C(40)-PdC(2) ) 86.97(13), C(2)-Pd-N(2) ) 83.20(12), C(40)-PdC(30) ) 93.68(13), N(2)-Pd-C(30) ) 95.99(12), C(20)N(2)-C(21) ) 123.5(2), C(20)-N(2)-Pd ) 116.6(2), C(21)N(2)-Pd ) 119.63(19), C(30)-N(3)-C(31) ) 177.8(3), C(40)-N(4)-C(41) ) 178.6(4), N(3)-C(30)-Pd ) 175.0(3), N(4)-C(40)-Pd ) 176.7(3).

Figure 8. Ellipsoid representation of 12c′Xy (50% probability). The anion is omitted. Selected bond lengths (Å) and angles (deg): Pd-C(30) ) 1.9474(18), Pd-C(1) ) 2.0471(18), Pd-N(2) ) 2.0616(14), Pd-C(40) ) 2.0654(19), N(1)-C(17) ) 1.138(2), N(2)-C(20) ) 1.290(2), N(2)-C(21) ) 1.447(2), N(3)-C(30) ) 1.150(2), N(3)-C(31) ) 1.403(2), N(4)-C(40) ) 1.156(2), N(4)-C(41) ) 1.397(2), C(4)C(5) ) 1.318(3); C(30)-Pd-C(1) ) 88.36(7), C(1)-Pd-N(2) ) 83.02(6), C(30)-Pd-C(40) ) 94.06(7), N(2)-Pd-C(40) ) 94.69(6), C(20)-N(2)-C(21) ) 121.62(14), C(20)-N(2)Pd ) 116.39(11), C(21)-N(2)-Pd ) 121.89(11), C(30)N(3)-C(31) ) 177.37(19), C(40)-N(4)-C(41) ) 176.43(18), N(3)-C(30)-Pd ) 177.96(17), N(4)-C(40)-Pd ) 178.85(16).

(2.130(6), 2.073(3), and 2.0686(16) Å, respectively). The same is observed when the Pd-N distances trans to the alkyl ligands in complexes 6a (2.1575(16) Å) and 6a′ (2.162(3) Å) are compared with those trans to the olefin ligand (2.1126(15) and 2.082(3) Å, respectively). The difference is still greater between the Pd-N distance



trans to the same alkyl ligand derived from norbornadiene (2.322(2) Å) and that trans to the imine ligand (2.074(2) Å) in the complex 10atBu. A similar pair of ligands causes a smaller effect in the Pd-CNXy distances in 12aXy (2.072(4) vs 1.933(3) Å) and 12c′Xy (2.0654(19) vs 1.9474(18) Å). All these data agree with the greater trans influence of carbon σ-donor ligands as compared to that of I-, olefin-, and N-donor ligands.

OdC) or intermolecular O-H‚‚‚O (4a′, acceptor OdC of acetone) or O-H‚‚‚OTf (6a, 6a′, 10atBu, and 12aXy) (see the Supporting Information). However, as the triflate is disordered in 6a′ and 12aXy, the structural parameters defining such interactions are not very reliable. C-H‚‚‚A hydrogen bond interactions, where A ) O and/or I, are also observed in 4a′, 4b, 6a, 10atBu, and 12c′Xy.

The structures of complexes 6, resulting after insertion of 1,5-cyclooctadiene, show that an endo insertion has been taken place (Figures 4 and 5), while those derived from norbornadiene (10atBu, 12aXy, and 12c′Xy) show an exo insertion (Figures 6-8). The structures of complexes 10atBu, 12aXy, and 12c′Xy (Figures 6-8) confirm the sequential insertion of first an isonitrile and then an olefin into a palladium-aryl bond. The CdC bond distance of the coordinated norbornadiene double bonds (6a, 1.382(3) Å; 6a′, 1.353(9) Å) is, as expected, longer than in the uncoordinated systems (10atBu, 1.328(4) Å; 12aXy, 1.313(5) Å; 12c′Xy, 1.318(3) Å).66

Acknowledgment. We are grateful for the financial support of the Ministerio de Ciencia y Tecnologıá, FEDER (BQU2001-0133), and the Ministerio de Educacioń, Cultura y Deporte for grants to M.J.L.S. and W.F.

Hydrogen Bonds. All phenol complexes form hydrogen bonds via the OH group, either intra- (2a′′, acceptor

Supporting Information Available: Listings of all refined and calculated atomic coordinates, anisotropic thermal parameters, and bond lengths and angles for 2a′′, 4a′‚Me2CO, 4b, 6a, 6a′, 10atBu, 12aXy, and 12c′Xy; data are also available as CIF files. This material is available free of charge via the Internet at http://pubs.acs.org. OM0496131 (66) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1. Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D. G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.

Reactivity of Ortho-Palladated Phenol Derivatives with Unsaturated

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