Palladium-Assisted Formation of an Indacenediide Ligand

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Organometallics 2009, 28, 5845–5847 DOI: 10.1021/om900770m

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Palladium-Assisted Formation of an Indacenediide Ligand Jose Vicente,* Eloı´ sa Martı´ nez-Viviente,* and Marı´ a-Jose Fernandez-Rodrı´ guez Grupo de Quı´mica Organomet alica, Dpto. de Quı´mica Inorg anica, Facultad de Quı´mica, Univ. de Murcia, Apdo. 4021, 30071, Murcia, Spain

Peter G. Jones* Institut f€ ur Anorganische und Analytische Chemie der Technischen Universit€ at Braunschweig. Postfach 3329, 38023, Braunschweig, Germany. E-mail: [email protected] Received September 4, 2009 Summary: The first palladium complex with an indacenediide ligand has been obtained by an unprecedented process involving the reaction of diphenylacetylene with a dipalladated 2,5distyrylbenzene complex.

The reaction of 1 with 2 equiv of diphenylacetylene and TlOTf (OTf = CF3SO3) affords the unprecedented dipalladated s-indacenediide complex syn-[(μ-η:η-1,5-dibenzyl-2,3,6,

The synthesis of Pd(II) aryl complexes and the study of their reactivity is a subject of great interest because of the implications for carbon-carbon and carbon-heteroatom bondforming reactions.1 Substituents ortho to the Pd atom may participate in the formation of organic compounds or influence the reactivity of these complexes.2 This has prompted us to study the chemistry of dipalladated benzene derivatives with substituents ortho to each palladium. Although the synthesis of some dipalladated benzene derivatives of this type has been reported,3-5 their reactivity in reactions involving the C-Pd bond is unexplored. In addition, with very few exceptions,4 these compounds were dipalladacycles with N- or, in some cases, P-donor5 groups. We communicate here the synthesis of a novel dipalladated 2,5-distyrylbenzene and its reaction with diphenylacetylene to generate a dicoordinated μ2-η:η-s-indacenediide ligand. This type of ligand is of interest because of the high delocalizability of its 14-π-electron system,6 which leads to a cooperative interaction between the two metallic centers.7 Homo- or heterobimetalated s- or as-indacenediide complexes have been reported with Fe,6,8-11 Co,9,10,12 Ni,9 Rh,6,13-16 and Ir14,15 but no Pd derivative had been synthesized until now. [C6H2{PdBr(tmeda)}2-1,4-((E)-CHdCHPh)2-2,5] (1) was obtained by oxidative addition of trans,trans-2,5-distyryl-2,4dibromobenzene17 to 2 equiv of “[Pd(dba)2]” ([Pd2(dba)3] 3 dba; dba=dibenzylideneacetone) in the presence of 2 equiv of tmeda (N,N,N0 ,N0 -tetramethylethylenediamine) (Scheme 1). Complex 1 is the first dipalladated benzene with alkenyl groups. It forms together with a small amount (less than 15%) of a more soluble monopalladated complex, from which it can be easily separated.

*To whom correspondence should be addressed. Regarding the synthesis and properties of compounds: [email protected] (J.V.); eloisamv@ um.es (E.M-V.). Web: http://www.um.es/gqo/. Regarding the X-ray diffraction studies: [email protected] (P.G.J.). (1) Tsuji, J. Palladium Reagents and Catalysts; Wiley: Chichester, U.K., 1995. Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457. Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2047. Hartwig, J. F. Acc. Chem. Res. 1998, 31, 852. Wolfe, J. P.; Wagaw, S.; Marcoux, J.-F.; Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805. Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176. Muci, A. R.; Buchwald, S. L. Top. Curr. Chem. 2002, 219, 131. Zeni, G.; Larock, R. C. Chem. Rev. 2004, 104, 2285. Larock, R. C.; Zeni, G. Chem. Rev. 2006, 106, 4644. Buchwald, S. L.; Mauger, C.; Mignani, G.; Scholz, U. Adv. Synth. Catal. 2006, 348, 23. Corbet, J. P.; Mignani, G. Chem. Rev. 2006, 106, 2651. Vicente, J.; Saura-Llamas, I. Comments Inorg. Chem. 2007, 28, 39.

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r 2009 American Chemical Society

Published on Web 09/22/2009

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Organometallics, Vol. 28, No. 20, 2009 Scheme 1

7-tetraphenyl-s-indacenediide){Pd(tmeda)2 }](OTf)2 (2) (Scheme 1), which was isolated as a single isomer. This is the first Pd-mediated synthesis of indacenediide ligands and could provide a general method for the synthesis of highly functionalized derivatives. Indeed, 1,5-dibenzyl-2,3,6,7-tetraphenyl-s-indene or derivatives thereof are not known. We suggest that the formation of 2 occurs via the pathway depicted in Scheme 2, involving the insertion of the alkyne into the aryl C-Pd bond (step A), followed by addition of the new C-Pd bond to the alkenyl substituent (step B). The successive β-hydride elimination (step C) and readdition (step D) would give a σ:σ-indacenodiide complex, which would isomerize (step E) to the more stable η:η derivative. We have (3) Trofimenko, S. Inorg. Chem. 1973, 12, 1215. Phillips, I. G.; Steel, P. J. J. Organomet. Chem. 1991, 410, 247. Chakladar, S.; Paul, P.; Mukherjee, A. K.; Dutta, S. K.; Nanda, K. K.; Podder, D.; Nag, K. J. Chem. Soc., Dalton Trans. 1992, 3119. Nanda, K. K.; Nag, K.; Venkatsubramanian, K.; Paul, P. Inorg. Chim. Acta 1992, 196, 195. Carina, R. F.; Williams, A. F.; Bernardinelli, G. J. Organomet. Chem. 1997, 548, 45. Lydon, D. P.; Rourke, J. P. Chem. Commun. 1997, 1741. Steenwinkel, P.; Gossage, R. A.; Maunula, T.; Grove, D. M.; van Koten, G. Chem. Eur. J. 1998, 4, 763. O'Keefe, B. J.; Steel, P. J. Organometallics 1998, 17, 3621. El Hatimi, A.; Gomez, M.; Jansat, S.; Muller, G.; Fontbardia, M.; Solans, X. J. Chem. Soc., Dalton Trans. 1998, 4229. Cardenas, D. J.; Echavarren, A. M.; Ramirez de Arellano, M. C. Organometallics 1999, 18, 3337. de Geest, D. J.; O'Keefe, B. J.; Steel, P. J. J. Organomet. Chem. 1999, 579, 97. Vicente, J.; Lyakhovych, M.; Bautista, D.; Jones, P. G. Organometallics 2001, 20, 4695. Mu~noz, M. P.; Martínez-Matute, B.; Fernandez-Rivas, C.; Cardenas, D. J.; Echavarren, A. M. Adv. Synth. Catal. 2001, 343, 338. Fernandez, A.; Pereira, E.; Fernandez, J. J.; L opez-Torres, M.; Suarez, A.; Mosteiro, R.; Pereira, M. T.; Vila, J. M. New J. Chem. 2002, 26, 895. Lopez-Torres, M.; Fernandez, A.; Fernandez, J. J.; Suarez, A.; Castrojuiz, S.; Pereira, M. T.; Vila, J. M. J. Organomet. Chem. 2002, 655, 127. Slater, J. W.; Rourke, J. P. J. Organomet. Chem. 2003, 688, 112. (4) Macdonald, P. M.; Hunter, A. D.; Lesley, G.; Li, J. Solid State Nucl. Magn. Reson. 1993, 2, 47. Vicente, J.; Abad, J. A.; Rink, B.; Hernandez, F.-S.; Ramírez de Arellano, M. C. Organometallics 1997, 16, 5269. Vila, J. M.; Gayoso, M.; Pereira, M. T.; Torres, M. L.; Fernandez, J. J.; Fernandez, A.; Ortigueira, J. M. Z. Anorg. Allg. Chem. 1997, 623, 844. (5) Bedford, R. B.; Blake, M. E.; Coles, S. J.; Hursthouse, M. B.; Scully, P. N. Dalton Trans. 2003, 2805. (6) Santi, S.; Ceccon, A.; Carli, F.; Crociani, L.; Bisello, A.; Tiso, M.; Venzo, A. Organometallics 2002, 21, 2679. Santi, S.; Orian, L.; Durante, C.; Bencze, E. Z.; Bisello, A.; Donolli, A.; Ceccon, A.; Benetollo, F.; Crociani, L. Chem. Eur. J. 2007, 13, 7933. (7) Beck, W.; Niemer, B.; Wieser, M. Angew. Chem., Int. Ed. Engl. 1993, 32, 923. Astruc, D. Acc. Chem. Res. 1997, 30, 383. Barlow, S.; O'Hare, D. Chem. Rev. 1997, 97, 637. McCleverty, J. A.; Ward, M. D. Acc. Chem. Res. 1998, 31, 842. Ceccon, A.; Santi, S.; Orian, L.; Bisello, A. Coord. Chem. Rev. 2004, 248, 683. (8) Davison, A.; Rudie, A. W. J. Organomet. Chem. 1979, 169, 69. Ijima, S.; Motoyama, I.; Sano, H. Chem. Lett. 1979, 1349. Gitany, R.; Paul, I. C.; Acton, N.; Katz, T. J. Tetrahedron Lett. 1970, 2723.

Vicente et al. Scheme 2

proposed a similar mechanism for the Pd-mediated synthesis of indenylpalladium complexes.18 Complexes 1 and 2 have been extensively studied by NMR (1D, COSY, HMBC, and HMQC experiments). A single set of 1H and 13C resonances for the halves of the molecules indicates the presence of a C2 symmetry axis (confirmed for 2 in the solid state). 13C chemical shifts are of diagnostic importance in the determination of the hapticity of Cpderived ligands.19 Thus, for η3-indenyls the ring junction carbons are deshielded with respect to the free ligand, while the opposite is observed for η5-indenyls.20,21 The same would apply to s-indacenediide ligands.16 In complex 2, the ring junction carbons resonate at higher frequencies (133.9 and 137.9 ppm) than in the s-indacenediide anion (127.8 ppm),22 suggesting an η3:η3 coordination mode for the ligand. The (9) Manrı´ quez, J. M.; Ward, M. D.; Reiff, W. M.; Calabrese, J. C.; Jones, N. L.; Carroll, P. J.; Bunel, E. E.; Miller, J. S. J. Am. Chem. Soc. 1995, 117, 6182. (10) Cary, D. R.; Webster, C. G.; Drewitt, M. J.; Barlow, S.; Green, J. C.; O’Hare, D. Chem. Commun. 1997, 953. (11) Roussel, P.; Cary, D. R.; Barlow, S.; Green, J. C.; Varret, F.; O’Hare, D. Organometallics 2000, 19, 1071. (12) Roussel, P.; Drewitt, M. J.; Cary, D. R.; Webster, C. G.; O’Hare, D. Chem. Commun. 1998, 2205. (13) Bonifaci, C.; Ceccon, A.; Gambaro, A.; Manoli, F.; Mantovani, L.; Ganis, P.; Santi, S.; Venzo, A. J. Organomet. Chem. 1998, 557, 97. (14) Ganis, P.; Ceccon, A.; K€ ohler, T.; Manoli, F.; Santi, S.; Venzo, A. Inorg. Chem. Commun. 1998, 1, 15. (15) Ceccon, A.; Bisello, A.; Crociani, L.; Gambaro, A.; Ganis, P.; Manoli, F.; Santi, S.; Venzo, A. J. Organomet. Chem. 2000, 600, 94. (16) Esponda, E.; Adams, C.; Burgos, F.; Chavez, I.; Manriquez, J. M.; Delpech, F.; Castel, A.; Gornitzka, H.; Riviere-Baudet, M.; Riviere, P. J. Organomet. Chem. 2006, 691, 3011. (17) Blum, J.; Zimmerman, M. Tetrahedron 1972, 28, 275. (18) Vicente, J.; Abad, J. A.; Bergs, R.; Jones, P. G.; Ramı´ rez de Arellano, M. C. Organometallics 1996, 15, 1422. Vicente, J.; Abad, J. A.; Bergs, R.; Ramirez de Arellano, M. C.; Martínez-Viviente, E.; Jones, P. G. Organometallics 2000, 19, 5597. (19) Kohler, F. H. Chem. Ber. 1974, 107, 570. (20) Baker, R. T.; Tulip, T. H. Organometallics 1986, 5, 839. Sui-Seng, C.; Enright, G. D.; Zargarian, D. Organometallics 2004, 23, 1236. (21) Westcott, S. A.; Kakkar, A. K.; Stringer, G.; Taylor, N. J.; Marder, T. B. J. Organomet. Chem. 1990, 394, 777. Zargarian, D. Coord. Chem. Rev. 2002, 233, 157. (22) Cohen, Y.; Klein, J.; Rabinovitz, M. J. Am. Chem. Soc. 1988, 110, 4634.

Communication

Figure 1. Thermal ellipsoid plot (30% probability level) of 2 3 CH2Cl2. The solvent, anions, and hydrogen atoms have been omitted for clarity.

large difference in chemical shift between the central and terminal “allylic carbons” (40.7 ppm in 2) has also been proposed as an indication of a strong allyl-ene distortion in indenyl complexes.23 The crystal structure of 2 3 CH2Cl2 has been determined by X-ray diffraction studies (Figure 1).24 A synfacial coordination of the two [Pd(tmeda)] moieties is observed, with approximate C2 symmetry, although some of the ring orientations depart from this ideal symmetry. Crystallographic investigations of other homonuclear bimetallic indacenediide complexes have revealed both syn10-12,15,16 and anti9,15 geometries. The indacenediide ligand partially loses its aromaticity upon coordination, as evidenced by its noticeable deviation from planarity (the atoms C(1)-C(7) (23) Ceccon, A.; Gambaro, A.; Santi, S.; Valle, G.; Venzo, A. J. Chem. Soc., Chem. Commun. 1989, 51. (24) X-ray analysis of 2 3 CH2Cl2. CCDC No. 742263. Crystal data: C65H70Cl2F6N4O6Pd2S2, space group P1, a = 13.6279(6) A˚, b = 13.8070(6) A˚, c = 19.2244(10) A˚, R = 93.796(4)°, β = 103.879(4)°, γ = 112.947(4)°, Z = 2. Data were recorded at 100(2) K on an Oxford Diffraction Nova A diffractometer to 2θ 152° using Cu KR radiation. The structure was refined anisotropically on F2 using the program SHELXL-97 ( Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112). Hydrogen atoms were included using a riding model. One triflate and the dichloromethane are disordered over two positions. The final wR2 was 0.113, with unweighted conventional R1 value 0.040, for 13 164 unique data, 875 parameters, and 447 restraints; S=1.05, maximum/ minimum ΔF 0.82/-1.37 e A˚-3.

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and C(10) are reasonably coplanar, with a mean deviation of 0.04 A˚, but C(8), C(9), C(11), and C(12) lie 0.39, 0.23, 0.45, and 0.26 A˚, respectively, out of this plane, all to the same side), thus reducing the steric interaction between the two [Pd(tmeda)] moieties. Consequently, the C(1)-C(7) (1.473(4) A˚), C(2)-C(9) (1.485(4) A˚), C(4)-C(10) (1.480(3) A˚), and C(5)-C(12) (1.478(4) A˚) bond distances are significantly longer than the others (1.391(4)-1.443(4) A˚). Similar deviations have been observed for other syn indacenediide complexes,12,15,16 while in the anti isomers the ligand usually retains its planarity.15 The distances of the Pd atoms to the “allylic” carbons (C(7)-C(9) for Pd(1) and C(10)-C(12) for Pd(2)) range between 2.186(2) and 2.221(2) A˚, significantly shorter than the distances to the “ene” carbons (C(1) and C(2) for Pd(1) and C(4) and C(5) for Pd(2)), between 2.541(2) and 2.626(3) A˚. Thus, the Δ(M-C) values21,25 for complex 2 are 0.367 A˚ (Pd(1)) and 0.391 A˚ (Pd(2)). These values are larger than those reported for any other dinuclear indacenediide complex (0-0.31 A˚),9-12,15,16 but they lie between those corresponding to η3 (0.5-0.9 A˚) and η5 coordination (0-0.2 A˚) in mononuclear indenyl complexes.21,25,26 Preliminary results confirm that the process reported here can be extended to other alkynes.

Acknowledgment. We thank the Ministerio de Educaci on y Ciencia (Spain), the FEDER (Project CTQ2007-60808/BQU), and the Fundaci on Seneca (04539/GERM/06) for financial support. M.J.F.-R. is grateful to the Ministerio de Educaci on y Ciencia (Spain) for a grant. Supporting Information Available: Text, figures, tables, and a CIF file giving experimental procedures, analytical and spectroscopic data of complexes 1 and 2, and crystallographic data for 2. This material is available free of charge via the Internet at http://pubs.acs.org. (25) Faller, W.; Crabtree, R. H.; Habib, A. Organometallics 1985, 4, 929. Marder, T. B.; Calabrese, J. C.; Roe, D. C.; Tulip, T. H. Organometallics 1987, 6, 2012. (26) Nesmeyanov, A. N.; Ustynyuk, N. A.; Makarova, L. G.; Andrianov, V. G.; Stuchkov, Y. T.; Andrae, S.; Ustynyuk, Y. A.; Malyugina, S. G. J. Organomet. Chem. 1978, 159, 189. Merola, J. S.; Kacmarcik, R. T.; Van Engen, D. J. Am. Chem. Soc. 1986, 108, 329. Kowalesky, R. M.; Reingold, A. L.; Trogler, W. C.; Basolo, F. J. Am. Chem. Soc. 1986, 108, 2460. Forschner, T. C.; Cutler, A. R.; Kullnig, R. K. Organometallics 1987, 6, 889. Kakkar, A. K.; Jones, S. F.; Taylor, N. J.; Collins, S.; Marder, T. B. J. Chem. Soc., Chem. Commun. 1989, 1454.