Synthesis of Monosubstituted Cyclopentadienyl Ruthenium

Aug 6, 2009 - (a) Albers , M. O.; Robinson , D. J.; Singleton , E. Coord. Chem. Rev. 1987 .... (c) Lomprey , J. R.; Selegue , J. P. Organometallics 19...
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Organometallics 2009, 28, 5529–5535 DOI: 10.1021/om900527v

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Synthesis of Monosubstituted Cyclopentadienyl Ruthenium Complexes from the Reactions of 6-Substituted Fulvenes with RuHCl(PPh3)3 Sunny Kai San Tse, Tongxun Guo, Herman Ho-Yung Sung, Ian Duncan Williams, Zhenyang Lin,* and Guochen Jia* Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong Received June 18, 2009

Reactions between 6-substitued fulvenes and the hydride complex RuHCl(PPh3)3 are described. Treatment of RuHCl(PPh3)3 with fulvenes without sp3-CH protons at the carbon R to the exocyclic carbon of fulvene produces cleanly monosubstituted cyclopentadienyl ruthenium complexes (η5-C5H4R)RuCl(PPh3)2 via hydride transfer to the electrophilic exocyclic carbon of fulvenes. When fulvenes containing sp3-CH protons at the carbon R to the exocyclic carbon were used, the reactions produce the expected (η5-C5H4R)RuCl(PPh3)2 complexes along with minor amounts of vinylcyclopentadienyl ruthenium complexes due to dehydrogenation.

Introduction Cyclopentadienyl ruthenium complexes of the type (η5cyclopentadienyl)RuCl(PR3)2 are useful precursors for organometallic synthesis and catalysis.1-3 It has been demonstrated that replacement of one or more of the hydrogens of the cyclopentadienyl (C5H5) ring by other substituents can lead to significant changes in the reactivity and catalytic properties due to steric and electronic effects introduced by these substituents. For example, in our study of ruthenium-catalyzed reactions, we found that Cp*RuCl(PPh3)2 can efficiently mediate the coupling reactions of azides with terminal alkynes to give selectively 1,5-disubstituted 1,2,3-triazoles, whereas the analogous complex

CpRuCl(PPh3)2 is much less effective in terms of both activity and selectivity.4 These observations prompted us to prepare various cyclopentadienyl complexes of the type (η5C5H4R)RuCl(PPh3)2 with different substituents on the Cp ring. The most common routes to complexes of the type CpSubRuCl(PR3)2 (CpSub = substituted cyclopentadienyl) include the reactions of CpSubH with RuCl3/PR3,5 the reactions of RuCl2(PPh3)3 with CpSubH6,7 or [CpSub]-, which are

*Corresponding author. E-mail: [email protected]. (1) For reviews on organometallic chemistry, see for example: (a) Albers, M. O.; Robinson, D. J.; Singleton, E. Coord. Chem. Rev. 1987, 79, 1. (b) Davies, S. G.; McNally, J. P.; Smallridge, A. J. Adv. Organomet. Chem. 1990, 30, 1. (c) Bennet, M. A.; Khan, K.; Wenger, E. In Comprehensive Organometallic Chemistry II; Abel, E. W., Stone, F. G., Wilkinson, G., Eds.; Pergamon Press: New York, 1995; Vol. 7, 473. (d) Jimenez-Tenorio, M.; Puerta, M. C.; Valerga, P. Eur. J. Inorg. Chem. 2004, 17. For reviews on catalysis, see for example: (e) Naota, T.; Takaya, H.; Murahashi, S. Chem. Rev. 1998, 98, 2599. (f) Barry, M.; Trost, B. M.; Frederiksen, M. U.; Rudd, M. T. Angew. Chem., Int. Ed. 2005, 44, 6630. (2) (a) Selegue, J. P.; Young, B. A.; Logan, S. L. Organometallics 1991, 10, 1972. (b) Bruce, M. I.; Hinterding, P.; Tiekink, E. R. T.; Skelton, B. W.; White, A. H. J. Organomet. Chem. 1993, 450, 209. (c) Lomprey, J. R.; Selegue, J. P. Organometallics 1993, 12, 616. (d) Le Lagadec, R.; Roman, E.; Toupet, L.; M€ uller, U.; Dixneuf, P. H. Organometallics 1994, 13, 5030. (e) de los Ríos, I.; Jimenez-Tenorio, M.; Puerta, M. C.; Valerga, P. J. Chem. Soc., Chem. Commun. 1995, 1757. (f) Kawano, Y.; Hashiva, M.; Shimoi, M. Organometallics 2006, 25, 4420. (g) Paul, F.; Ellis, B. G.; Bruce, M. I. Toupet, L.; Roisnel, T.; Costuas, K.; Halet, J.-F.; Lapinte, C. Organometallics 2006, 25, 649. (h) Bruce, M. I.; Costuas, K.; Davin, T.; Ellis, B. G.; Halet, J.-F.; Lapinte, C.; Low, P. J.; Smith, M. E.; Skelton, B. W.; Toupet, L.; White, A. H. Organometallics 2005, 24, 3864. (i) Bruce, M. I.; Ellis, B. G.; Low, P. J.; Skelton, B. W.; White, A. H. Organometallics 2003, 22, 3184. (j) Bruce, M. I.; Skelton, B. W.; White, A. H.; Zaitseva, N. N. J. Organomet. Chem. 2002, 650, 141. (k) Ciardi, C.; Reginato, G.; Gonsalvi, L.; de los Ríos, I.; Romerosa, A.; Peruzzini, M. Organometallics 2004, 23, 2020. (l) Fan, L.; Einstein, F. W. B.; Sutton, D. Organometallics 2000, 19, 684. (m) Frost, B. J.; Mebi, C. A. Organometallics 2004, 23, 5317.

(3) Recent examples of catalytic reactions: (a) Tenaglia, A.; Marc, S. J. Org. Chem. 2008, 73, 1397. (b) Yang, C. W.; Liu R. S. Tetrahedron Lett. 2007, 48, 5887. (c) Tenaglia, A.; Marc, S. J. Org. Chem. 2006, 71, 3569. (d) Movassaghi, M.; Hill, M. D. J. Am. Chem. Soc. 2006, 128, 4592. (e) Del Zotto, A.; Baratta, W.; Sandri, M.; Verardo, G.; Rigo, P. Eur. J. Inorg. Chem. 2004, 524. (f) Murakami, M.; Hori, S. J. Am. Chem. Soc. 2003, 125, 4720– 4721. (g) Kirss, R. U.; Ernst, R. D.; Arif, A. M. J. Organomet. Chem. 2004, 689, 419. (h) Pedro, F. M.; Santos, A. M.; Baratta, W.; K€uhn, F. E. Organometallics 2007, 26, 302–309. (i) Tenaglia, A.; Marc, S. J. Org. Chem. 2008, 73, 1397. (j) Baratta, W.; Herrmann, W. A.; Kratzer, R. M.; Rigo, P. Organometallics 2000, 19, 3664. (k) Trost, B. M.; Livingston, R. C. J. Am. Chem. Soc. 2008, 130, 11970. (l) Tenaglia, A.; Marc, S. J. Org. Chem. 2006, 71, 3569. (m) Miura, Y.; Shibata, T.; Satoh, K.; Kamigaito, M.; Okamoto, Y. J. Am. Chem. Soc. 2006, 128, 16 026. (4) Boren, B. C.; Narayan, S.; Rasmussen, L. K.; Zhang, L.; Zhao, H.; Lin, Z.; Jia, G.; Fokin, V. V. J. Am. Chem. Soc. 2008, 130, 8923. (5) See for example: (a) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg. Synth. 1982, 21, 78. (b) Roemming, C.; Smith, K.-T.; Tilset, M. Inorg. Chim. Acta 1997, 259, 281. (c) Wilczewski, T.; Bochenska, M.; Biernat, J. F. J. Organomet. Chem. 1981, 215, 87. (d) Liu, J. F.; Huang, S. L.; Lin, Y. C.; Liu, Y. H.; Wang, Y. Organometallics 2002, 21, 1355. (e) Reventos, L. B.; Alonso, A. G. J. Organomet. Chem. 1986, 309, 179. (f) Bruce, M. I.; Windsor, N. J. Aust. J. Chem. 1977, 30, 1601. (g) Baratta, W.; Del Zotto, A.; Rigo, P. Organometallics 1999, 18, 5091. (h) Romerosa, A.; Campos-Malpartida, T.; Lidrissi, C.; Saoud, M.; Serrano-Ruiz, M.; Peruzzini, M.; Garrido-Cardenas, J. A.; García-Maroto, F. Inorg. Chem. 2006, 45, 1289. (6) (a) Tsuno, T.; Brunner, H.; Katano, S.; Kinjyo, N.; Zabel, M. J. Organomet. Chem. 2006, 691, 2739. (b) Slawin, A. M. Z.; Williams, D. J.; Crosby, J.; Ramsden, J. A.; White, C. J. Chem. Soc., Dalton Trans. 1988, 2491. (c) Schwink, L.; Vettel, S.; Knochel, P. Organometallics 1995, 14, 5000. (7) A similar reaction between C5H6 and RuHCl(CO)(PiPr3)2 ocomez, A. V.; curred to give CpRuH(CO)(PiPr3). Esteruelas, M. A.; G Lahoz, F. J.; L opez, A. M.; O~ nate, E.; Oro, L. A. Organometallics 1996, 15, 3423.

r 2009 American Chemical Society

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generated from the reactions of CpSubH with bases such as BuLi, NaH, or tBuOK,8 the reactions of RuCl2(PPh3)3 with substituted cyclopentadienes having a TMS group on the ring,9 and the reactions of PPh3 with [CpSubRuCl2]2, which were usually in turn made from the reactions of CpSubH with RuCl3.10 All the preparations require the availability of CpSubH. While the preparations are efficient in many cases, difficulty may be encountered in other cases, due to the unavailability or the low stability of CpSubH starting materials. Consequently, other routes to CpSubRuCl(PPh3)2 have been sought after. Examples of these include the reactions of RuCl2(PPh3)3 with [CpSub]- anions, which are generated in situ from the reactions between spiro[2.4]hepta-4,6-diene and nucleophiles,11 and the reactions of RuCl2(PPh3)3 with lithium fulvenolates C5H4(COLiR).12 Substituted fulvenes, which are easily accessible, have been demonstrated to be useful starting materials for the preparation of cyclopentadienyl complexes.13 A number of cyclopentadienyl complexes have been obtained from fulvenes by first converting fulvenes to cyclopentadienyl anions via their reactions with reducing agents such as sodium and calcium14 or with nucleophiles such as lithium or Grignard reagents,15 LiAlH4 or LiBHEt3,16 followed by the reactions of the cyclopentadienyl anions with suitable precursors. It has also been demonstrated that early transition metal cyclopentadienyl complexes could be obtained from the insertion reactions of fulvenes with metal alkyl or hydride complexes. (8) Recent examples using BuLi as the base: (a) Vogelgesang, J.; Frick, A.; Huttner, G.; Kircher, P. Eur. J. Inorg. Chem. 2001, 949. (b) Trost, B. M.; Vidal, B.; Thommen, M. Chem.;Eur. J. 1999, 5, 1055. (c) Shaw, A. P.; Guan, H.; Norton, J. R. J. Organomet. Chem. 2008, 693, 1382. Recent examples using NaH as the base: (d) Sun, Y.; Chan, H. S.; Dixneuf, P. H.; Xie, Z. Chem. Commun. 2004, 2588. Recent examples using tBuOK as the base: (e) Bola~ no, S.; Gonsalvi, L.; Zanobini, F.; Vizza, F.; Bertolasi, V.; Romerosa, A.; Peruzzini, M. J. Mol. Catal. (A) 2004, 224, 61. Recent examples using NaHBEt3 as the base: (f) Kaulen, C.; Pala, C.; Hu, C.; Ganter, C. Organometallics 2001, 20, 1614. (g) Lam, Y. F.; Yin, C.; Yeung, C. H.; Ng, S. M.; Jia, G.; Lau, C. P. Organometallics 2002, 21, 1898. (9) Zeijden, A.; Jimenez, J.; Mattheis, C.; Wagner, C.; Merzweiler, K. Eur. J. Inorg. Chem. 1999, 1919. (10) (a) Lehmkuhl, H.; Bellenbaum, M.; Grundke, J.; Mauermann, H.; Kr€ uger, C. Chem. Ber. 1988, 121, 1719. (b) Chinn, M. S.; Heinekey, D. M. J. Am. Chem. Soc. 1990, 112, 5166. (c) Jia, G.; Lough, A. J.; Morris, R. H. Organometallics 1992, 11, 161. (d) Dutta, B.; Scolaro, C.; Scopelliti, R.; Dyson, P. J.; Severin, K. Organometallics 2008, 27, 1355. (e) Akbayeva, D. N.; Gonsalvi, L.; Oberhauser, W.; Peruzzini, M.; Vizza, F.; Br€uggeller, P.; Romerosa, A.; Sava, G.; Bergamo, A. Chem. Commun. 2003, 264. (f) Palacios, M. D.; Puerta, M. C.; Valerga, P.; Lledos, A.; Veilly, E. Inorg. Chem. 2007, 46, 6958. (g) Tilley, T. D.; Grubbs, R. H.; Bercaw, J. Organometallics 1984, 3, 274. (h) Dutta, B.; Solari, E.; Gauthier, S.; Scopelliti, R.; Severin, K. Organometallics 2007, 26, 4791. (11) Gorman, J. S. T.; Lynch, V.; Pagenkopf, B. L.; Young, B. Tetrahedron Lett. 2003, 44, 5435. (12) Kunz, D.; Fr€ ohlich, R.; Erker, G. Organometallics 2001, 20, 572. (13) (a) Erker, G.; Kehr, G.; Fr€ ohlich, R. Organometallics 2008, 27, 3. (b) Strohfeldt, K.; Tacke, M. Chem. Soc. Rev. 2008, 37, 1174. (c) Coville, N. J.; Plooy, K. E.; Pickl, W. Coord. Chem. Rev. 1992, 116, 1. (14) Use of Na, see for example: (a) Fischer, M.; B€ onzli, P.; Stofer, B.; Neuenschwander, M. Helv. Chim. Acta 1999, 82, 1509. Use of Ca, see for example: (b) Kane, K. M.; Shapiro, P. J.; Vij, A.; Cubbon, R.; Rheingold, A. L. Organometallics 1997, 16, 4567. (c) Sinnema, P. J.; H€ohn, B.; Hubbard, R. L.; Shapiro, P. J.; Twamley, B.; Blumenfeld, A.; Vij, A. Organometallics 2002, 21, 182. (d) Eisch, J. J.; Shi, X.; Owuor, F. A. Organometallics 1998, 17, 5219. (15) Suzuka, T.; Ogasawara, M.; Hayashi, T. J. Org. Chem. 2002, 67, 3355. (16) Use of LiAlH4: (a) Plazuk, D.; Le Bideau, F.; Perez-Luna, A.; Stephan, E.; Vessierres, A.; Zakrzewski, J.; Jaouen, G. Appl. Organomet. Chem. 2006, 20, 168. (b) Hopf, H., Sankararaman, S., Dix, I., Jones, P. G., Alt, H. G.; Licht, A. Eur. J. Inorg. Chem. 2002, 123. Use of LiBHEt3: (c) Claffey, J.; Hogan, M.; M€uller-Bunz, H.; Pampillon, C.; Tacke, M. J. Organomet. Chem. 2008, 693, 526. (d) Strohfeldt, K.; M€uller-Bunz, H.; Pampill on, C.; Sweeney, N. J.; Tacke, M. Eur. J. Inorg. Chem. 2006, 4621.

Tse et al. Scheme 1

For example, complexes M(CH2Ph)4 (M=Zr, Hf) react with 6,60 -dimethylfulvenes to give the insertion products (C5H4CMe2CH2Ph)M(CH2Ph)3;17 Bu2ZrCl2 reacts with 6-arylfulvenes to give bis(benzylcyclopentadienyl)zirconium dichloride complexes presumably through the insertion reaction of a hydride intermediate generated in situ from β-hydrogen elimination.18 In light of the success in the preparation of cyclopentadienyl complexes of early transition metals via insertion reactions of fulvene derivatives, one might expect that ruthenium cyclopentadienyl complexes may also be easily prepared from the reactions of fulvenes with ruthenium hydride complexes. However, such a possibility has not been previously explored. In this work, we have investigated reactions between RuHCl(PPh3)3 and 10 fulvene derivatives, which enable us to obtain a series of (η5-C5H4R)RuCl(PPh3)2.

Results and Discussion Synthesis of Fulvenes. The structures of fulvene derivatives used in this work are shown in Scheme 1. They were prepared from the reactions of freshly distilled cyclopentadiene with the corresponding aldehydes or ketones in methanol in the presence of 2 equiv of pyrrolidine or NaOMe as the base, as shown in eq 1 in Scheme 1.19 Except 6-pyrenyl- and 6phenanthrylfulvenes, all the fulvenes are known compounds. The identities of the fulvenes have been confirmed by NMR spectroscopy. Reactions of RuHCl(PPh3)3 with Fulvenes without sp3-CH Protons at the carbon r to the Exocyclic (C6) Carbon. Treatment of RuHCl(PPh3)3 with fulvenes 1S-6S in a 1:1.5 molar ratio in dichloromethane at room temperature readily produced the corresponding monosubstituted cyclopentadienyl ruthenium complexes 1-6 (Scheme 2). As monitored by in situ 31P{1H} NMR spectroscopy, the reactions are essentially completed in 1 h, giving the cyclopentadienyl complexes (η5-C5H4R)RuCl(PPh3)2 as the only products. The formation of (η5-C5H4R)RuCl(PPh3)2 is visually marked by a color change of the solution from reddishpurple to deep orange. A slight excess of fulvene was used in our experiments in order to ensure the complete consumption of the hydride complex in a short reaction time. The airstable yellow complexes were obtained in moderate to high yields after recrystallization from n-hexane and diethyl ether. The new complexes have been characterized by NMR and elemental analysis. Consistent with the structures, the (17) Rogers, J. S.; Lachicotte, R. J.; Bazan, G. C. Organometallics 1999, 18, 3976. (18) Eisch, J. J.; Owuor, F. A.; Shi, X. Organometallics 1999, 18, 1583. (19) Stone, K. J.; Little, R. D. J. Org. Chem. 1984, 49, 1849.

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Figure 1. ORTEP drawing of 2. Except those on C6-C8, hydrogen atoms are omitted for clarity. Thermal ellipsoids are shown at the 35% probability level. Selected bond lengths (A˚) and angles (deg): average Ru1-C(Cp), 2.207; Ru1-Cl1, 2.4359(12); Ru1-P1, 2.2988(10); Ru1-P2, 2.3314(11); C6C7, 1.489(5); C7-C8, 1.311(6); P1-Ru1-P2, 100.36(4); Ru1C1-C6, 125.3(3); C6-C7-C8, 123.4(5); C7-C8-C9, 129.0(5).

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Figure 2. ORTEP drawing of 4. Thermal ellipsoids are shown at the 40% probability level. Selected bond lengths (A˚) and angles (deg): average Ru1-C(Cp), 2.211; Ru1-Cl1, 2.4462(7); Ru1-P1, 2.3036(7); Ru1-P2, 2.3195(8); P1-Ru1P2, 100.38(3); Ru1-C1-C6, 126.27(19).

Scheme 2

31

P{1H} NMR spectra show a sharp singlet peak in the region 38-40 ppm (depending on the pendant group). The 1 H NMR spectra display two signals for protons of cyclopentadienyl rings at ca. 4.3 and 3.6 ppm. The structures of the complexes (η5-C5H4CH2CHdCHPh)RuCl(PPh3)2 (2) (Figure 1), (η5-C5H4CH2(pyrenyl))RuCl(PPh3)2 (4) (Figure 2), and (η5-C5H4CHPh2)RuCl(PPh3)2 (6) (Figure 3) have been confirmed by X-ray crystallography. In each case, the molecule adopts a piano stool structure with two PPh3 and a Cl ligand as the legs. The Cl ligand settles under the substituent of the cyclopentadienyl ring. The P-Ru-Cl angles

Figure 3. ORTEP drawing of 6. Thermal ellipsoids are shown at the 35% probability level. Selected bond lengths (A˚) and angles (deg): average Ru1-C(Cp), 2.2219; Ru1-Cl1, 2.4420(4); Ru1-P1, 2.2961(4); Ru1-P2, 2.3306(4); P1-Ru1-P2, 99.929(14); Ru1-C1-C6, 126.36(10).

(20) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1981, 1398.

(close to 90°) are similar to those (88.23°, 89.15°) in CpRuCl(PPh3)2.20 The P-Ru-P angles (close to 100°) are slightly smaller than that of CpRuCl(PPh3)2 (104°), presumably due to

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Organometallics, Vol. 28, No. 18, 2009 Scheme 3

the steric effects of the substituents. The carbon directly bound to the Cp ring is nearly coplanar with the Cp ring, while the remaining part of the substituent bends away from the metal center. The average carbon-metal distances of the Cp0 Ru fragments as well as the Ru-Cl and Ru-P bond distances are similar to those reported for CpRuCl(PPh3)2. As mentioned above, the exocyclic C6 carbons of fulvenes are electrophilic and can be attacked by nucleophiles. In our reactions, the cyclopentadienyl ligand is presumably generated via a hydride transfer from RuHCl(PPh3)3 to the C6 carbon of the fulvenes. Reactions of RuHCl(PPh3)3 with Fulvenes with Protons at the Carbon r to the C6 carbon. When fulvenes containing sp3-CH protons at the carbon R to the C6 carbon (7S-10S) were allowed to react with RuHCl(PPh3)3, the reactions generally give two products: an expected (η5-C5H4R)RuCl(PPh3)2 complex as the major product and a formally dehydrogenated product, η5-vinylcyclopentadienyl ruthenium complex, as the minor product. The relative amount of the two products is dependent on the structures of the starting fulvenes (Scheme 3). The reaction of RuHCl(PPh3)3 with 6-(cyclohexyl)fulvene gives (η5-C5H4-cyclohexyl)RuCl(PPh3)2 (8A) and [(η5-C5H4-cyclohexenyl)RuCl(PPh3)2 (8B) in a molar ratio of ca. 4.5:1. It can be demonstrated that the ratio of the complexes 8A and 8B does not change appreciably when the reaction was carried out under a hydrogen atmosphere. Similar results were observed when 6-(cyclopentyl)fulvene (7S) and 6-(cycloheptyl)fulvene (9S) were allowed to react with RuHCl(PPh3)3. For 6-(cyclopentyl)fulvene, the reaction produced the expected product 7A and the dehydrogentated product 7B in a molar ratio of 6.6:1. For 6-(cycloheptyl)fulvene, the reaction produced 9A and 9B in a molar ratio of 1.3:1. When the noncylic fulvene 6-(isopropyl)fulvene (10) was used, the reaction produced 10A and 10B in a molar ratio of 13.1:1. Although our attempts to separate the products by recrystallization or column chromatography were unsuccessful, the identities of the products can be deduced from their spectroscopic data. For example, for the reaction of

Tse et al. Scheme 4

6-(cycloheptyl)fulvene, the major product exhibits a 31P{1H} signal at 40.34 ppm in the 31P{1H} NMR spectrum and 1H signals at 4.20 and 3.59 ppm assignable to protons of a cyclopentadienyl ring in the 1H NMR spectrum. The similarity in the NMR data of the product and complexes 1-6 and 7A suggests that they have similar coordination spheres. Therefore the major product was assigned to complex 9A (Scheme 3). The minor product displays a 31P{1H} signal with a chemical shift very similar to that of the major product. The 1H NMR spectrum shows, in addition to the signals of protons of the cyclopentadienyl ring at 4.54 and 3.48 ppm, a vinyl proton signal at 6.33 ppm. Consistent with the presence of the vinyl group, the 13C{1H} NMR spectrum exhibits singlet vinyl signals at 132 (dCH) and 138 ppm CpCdCH) for the minor product. Scheme 4 shows plausible pathways for the formation of the expected (η5-C5H4R)RuCl complexes 7A-10A (represented as A) and the vinylcyclopentadienyl complexes 7B-10B (represented as B). The hydride complex RuHCl(PPh3)3 may initially react with a fulvene to give the fulvene complex C. Complex A can be generated via intermediate D formed by an insertion reaction of C in which the hydride is transferred to the C6 carbon of the fulvene. The vinylcyclopentadienyl product B is formally a dehydrogenated product of A. However, it can be demonstrated that once 8A is formed, it can not be converted to 8B. Thus complex A is not the precursor to complex B. Vinylcyclopentadienyl complexes of early transition metals can be prepared from deprotonation reactions of fulvenes. For example, Zr(NMe2)4 reacts with 6,60 -(dimethyl)fulvene to give (η5-C5H4(CMedCH2))Zr(NMe2)3,16 and 6,60 -(dimethyl)fulvene reacts with LDA/Mo(CO)6 to give a vinylcyclopentadienyl complex.21 However, the basicity of the ruthenium hydride of RuHCl(PPh3)3 may not be strong enough to deprotonate fulvene. We therefore propose that vinylcyclopentadienyl complex B may be formed from 16e- ruthenium fulvene hydride complex E, generated from dissociation of PPh3 from C. Oxidative addition of an allylic C-H bond (at the carbon R to the C6 of the fulvene) of E would give intermediate F. B can then be formed by reductive elimination of H2 followed by (21) Macomber, D. W.; Hart, W. P.; Rausch, M. D.; Priester, R. D.; Pittman, C. U. Jr. J. Am. Chem. Soc. 1982, 104, 884.

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rearrangement. Relevant observations include the reaction of 1,4-pentadienes (C5H8) with RuHCl(PPh3)3 to give the pentadienyl complex (η5-C5H7)RuCl(PPh3)222a and the reaction of 1,3-cycloheptadiene (C7H10) with RuHCl(PPh3)3 to give cyclopentadienyl complex (η5-C7H9)RuCl(PPh3)2.22b Consistent with the mechanism, it was observed that the formation of vinyl-cyclopentadienyl product is inhibited when reaction of RuHCl(PPh3)3 with cycloheptylfulvene (9S) was carried out in the presence of a 10-fold excess of PPh3, which suppressed the formation of intermediates E and F. In summary, reactions of RuHCl(PPh3)3 with fulvenes without sp3-CH protons at the carbon R to the exocyclic carbon of the fulvene provide a simple and efficient method for the synthesis of monosubstituted cyclopentadienyl ruthenium complexes of the type (η5-C5H4R)RuCl(PPh3)2 via hydride transfer to the electrophilic exocyclic carbon of fulvenes. When fulvenes containing sp3-CH protons at the carbon R to the exocyclic carbon are used, the reactions also give the expected complexes as the major products along with small amounts of vinylcyclopentadienyl complexes due to elimination of H2.

Experimental Section All manipulations were carried out under a nitrogen atmosphere using standard Schlenk techniques, unless otherwise stated. Solvents were distilled under nitrogen from sodium and benzophenone (n-hexane, diethyl ether), sodium (THF, benzene), or calcium hydride (CH2Cl2). The starting materials RuHCl(PPh3)323 1S-2S, 4S-6S,19 3S,24 9S,25 and 10S26 were prepared following the procedures described in the literature. All other reagents were used as purchased from Aldrich Chemical Co. Microanalyses were performed by M-H-W Laboratories (Phoenix, AZ). 1H, 13C{1H}, and 31P{1H} NMR spectra were collected on a Bruker-400 spectrometer (400 MHz) or a Bruker ARX-300 spectrometer (300 MHz). 1H and 13C NMR shifts are relative to TMS, and 31P chemical shifts are relative to 85% H3PO4. MS spectra were recorded on a Finnigan TSQ7000 spectrometer. General Procedure for the Preparation of Fulvenes. An aldehyde or ketone (14.69 mmol) and freshly distilled cyclopentadiene (3.00 mL, 36.76 mmol, 2.5 equiv) were mixed in MeOH (15 mL). Pyrrolidine (2.40 mL, 29.22 mmol, 2 equiv) was added dropwisely to the mixture, and the mixture was stirred at room temperature. The reaction was monitored by TLC on an hourly basis. After the completion of the reaction, acetic acid (1.20 mL, 20.94 mmol) was added and the mixture was stirred for a further 30 min. The product was extracted with dichloromethane (20 mL  2), washed with a brine solution (20 mL  2), and dried over MgSO4. The product was purified by column chromatography using n-hexane as the eluent. 6-Pyrenylfulvene (4S). 1-Pyrenecarboxaldehyde, 402 mg, 1.74 mmol; reaction time, 64 h; yield, 170 mg (orange solid), 34.6%. 1H NMR (400 MHz, acetone-d6): δ 8.57 (d, J=9.2 Hz, 1H), 8.44 (s, 1H), 8.04 (s, 1H), 8.38 (s, 2H), 8.33 (m, 2H), 8.26 (dd, J=17.6, 9.2 Hz, 2H), 8.17 (t, J=7.6 Hz, 1H), 6.83 (m, 1H), 6.77 (m, 1H), 6.70 (m, 2H). 13C{1H} NMR (100.62 MHz, acetone-d6): δ 146.6, 134.99, 134.85, 131.26, 130.72, 130.25, (22) (a) Mann, B. E.; Manning, P. W.; Spencer, C. M. J. Organomet. Chem. 1986, 312, C64. (b) Grassi, M.; Mann, B. E.; Manning, P.; Spencer, C. M. J. Organomet. Chem. 1986, 307, C55. (23) Hallman, P. S.; McGarvey, B. R.; Wilkinson, G. J. Chem. Soc. (A) 1968, 3143. (24) Imafuku, K.; Inoue, K. Bull. Chem. Soc. Jpn. 1982, 55, 3242. (25) Erden, I.; Xu, F. P.; Sadoun, A.; Smith, W.; Sheff, G.; Ossun, M. J. Org. Chem. 1995, 60, 813. (26) Jeffery, J.; Probitts, E. J.; Mawby, R. J. J. Chem. Soc., Dalton Trans. 1984, 2423.

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130.21, 129.30, 128.89, 127.71, 126.70, 126.17, 125.78, 125.28, 125.14, 124.22, 123.86, 123.71, 122.80, 120.45. MS (TOF CIþ): m/z 279.11 (M). 6-Phenanthrenylfulvene (5S). Phenanthrene-9-carboxaldehyde, 605 mg, 2.93 mmol; reaction time, 72 h; yield, 503 mg (orange solid), 67.5%. 1H NMR (400 MHz, CDCl3): δ 8.76 (d, J=8.4 Hz, 1H), 8.70 (d, J=8.4 Hz, 1H), 8.14 (d, J=8 Hz, 1H), 7.96-7.93 (m, 2H), 7.87 (s, 1H), 7.74-7.62 (m, 4H), 6.69-6.62 (m, 2H), 6.53 (d, J = 2 Hz, 1H), 6.52 (d, J=1.6 Hz, 1H). 13C{1H} NMR (100.62 MHz, CDCl3): δ 148.03, 136.79, 135.31, 133.12, 132.83, 132.01, 131.97, 131.48, 131.22, 130.91, 129.92, 128.05, 127.61, 127.59, 127.50, 126.45, 126.01, 123.74, 123.22, 122.09. MS (TOF CIþ): m/z 255.11 (M þ H). General Procedure for the Synthesis of (η5-C5H4R)RuCl(PPh3)2 (1-10). A fulvene solution in CH2Cl2 (6 mL) was added dropwisely to a solution of RuHCl(PPh3)3 in CH2Cl2 (4 mL). The mixture was stirred at room temperature for 2 h. After the completion of the reaction, the solvent was removed by evaporation under vacuum. The residue was washed with n-hexane and Et2O and then dried to afford the corresponding cyclopentadienyl complexes. (η5-C5H4CHt2Bu)RuCl(PPh3)2 (1). 6-Butylfulvene (1S), 56 mg, 0.417 mmol; RuHCl(PPh3)3, 255 mg, 0.276 mmol; yield, 172 mg, 78.3%. 1H NMR (400 MHz, C6D6): δ 7.83 (br, 12H, PPh3), 7.07 (br, 18H, PPh3), 4.30 (s, 2H, Cp), 3.63 (s, 2H, Cp), 2.52 (s, 2H, CH2), 1.05 (s, 9H, CH3). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 138.87 (m), 133.90, 128.68, 127.42 (PPh3), 104.64, 82.13, 76.43 (C5H4), 41.60 (CpCH2), 30.86 (CMe3), 29.52 (CMe3). 31P{1H} NMR (162 MHz, C6D6): δ 39.9 (s). Anal. Calcd for C46H45ClP2Ru: C, 69.38; H, 5.7. Found: C, 69.60; H, 5.61. (η5-C5H4CH2CHdCHPh)RuCl(PPh3)2 (2). 2S, 99 mg, 0.549 mmol; RuHCl(PPh3)3, 308 mg, 0.333 mmol; yield, 206 mg, 73.4%. 1H NMR (300 MHz, C6D6): δ 7.82 (br, 14H, PPh3), 7.40 (d, J=7.3 Hz, 2H, Ph), 7.24 (d, J=7.3 Hz, 2H, Ph), 7.16 (m, 1H, Ph), 7.06 (br, 16H, PPh3), 6.73-6.56 (m, 2H, CHdCH), 4.30 (s, 2H, Cp), 3.69 (d, J=4.83 Hz, 2H, CpCH2), 3.61 (s, 2H, Cp). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 138.92 (m), 134.05 (virtual t, J = 5.13 Hz), 128.92, 127.62 (virtual t, J = 4.45 Hz) (PPh3), 137.83, 128.64, 127.23, 126.24 (dCHPh), 131.19, 129.16 (CHdCHPh), 107.47, 80.17 (t, J=4.45 Hz), 76.91 (C5H4), 30.62 (CpCH2). 31P{1H} NMR (121.47 MHz, C6D6): δ 41.09 (s). Anal. Calcd for C49H41ClP2Ru: C, 71.29; H, 5.15. Found: C, 71.56; H, 5.10. (η5-C5H4CH2tolyl)RuCl(PPh3)2 (3). 3S, 84 mg, 0.499 mmol; RuHCl(PPh3)3, 298 mg, 0.322 mmol; yield, 165 mg, 61.6%. 1H NMR (400 MHz, acetone-d6): δ 7.60 (br, 12H, PPh3), 7.43 (t, J= 7.2 Hz, 6H, PPh3), 7.33 (m, 12H, PPh3), 7.25 (dd, J=8 Hz, 4H, C6H4-Me), 4.08 (s, 2H, Cp), 3.70 (s, 2H, CH2), 3.55 (s, 2H, Cp), 2.41 (s, 3H, C6H4-Me). 13C{1H} NMR (75.5 MHz, CD2Cl2): δ 138.5 (m), 133.90 (virtual t, J=4.9 Hz), 128.77, 127.47(virtual t, J = 4.5 Hz) (PPh3), 137.93, 135.66, 129.07 (Carom. of Toyl), 108.11, 80.21, 76.87 (C5H4), 32.75 (CpCH2), 20.77 (CH3 of Toyl). 31P{1H} NMR (161.97 MHz, acetone-d6): δ 39.4 (s). Anal. Calcd for C49H43ClP2Ru: C, 70.88; H, 5.22. Found: C, 71.06; H, 5.18. (η5-C5H4CH2pyrenyl)RuCl(PPh3)2 (4). 4S, 141 mg, 0.500 mmol; RuHCl(PPh3)3, 308 mg, 0.333 mmol; yield, 207 mg, 66.1%. 1H NMR (400 MHz, CDCl3): δ 8.60 (d, 1H, pyrene), 8.25 (m, 5H, pyrene), 8.12 (s, 3H, pyrene), 7.56 (br, 12H, PPh3), 7.33 (m, 8H, PPh3), 7.26 (m, 10H, PPh3), 4.51 (s, 2H, Cp), 4.19 (s, 2H, CH2), 3.42 (s, 2H, Cp). 31P{1H} NMR (161.97 MHz, CDCl3): δ 39.71 (s). Anal. Calcd for C58H45ClP2Ru: C, 74.07; H, 4.82. Found: C, 74.20; H, 5.00. (η5-C5H4CH2phenanthrenyl)RuCl(PPh3)2 (5). 5S, 100 mg, 0.393 mmol; RuHCl(PPh3)3, 254 mg, 0.275 mmol; yield, 175 mg, 69.44%. 1H NMR (400 MHz, CDCl3): δ 8.71 (d, J = 6.8 Hz, 1H, phenanthrene), 8.64 (d, J=6.8 Hz, 1H, phenanthrene), 8.23 (d, J = 6.8 Hz, 1H, phenanthrene), 7.83 (d, J = 6.8 Hz, 1H, phenanthrene), 7.70 (s, 1H, phenanthrene), 7.61 (m, 4H,

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Table 1. Crystal Data and Structure Refinement for 2, 4, and 6

formula fw wavelength, A˚ cryst syst space group a, A˚ b, A˚ c, A˚ R, deg β, deg γ, deg V, A˚ Z dcalcd, g cm-3 abs coeff, mm-1 F(000) θ range, deg no. of rflns no. of indep rflns no. of data/restraints/params goodness of fit on F2 final R indices (I > 2σ(I)) largest diff peak and hole, e A˚-3

2

4

6

C50H43ClP2Ru 842.30 0.71073 monoclinic P2(1)/c 15.2938(17) 23.070(3) 11.2784(12) 90 97.272(2) 90 3947.3(7) 4 1.417 0.582 1736 1.34-26.00 21 658 7683 (R(int) = 0.1035) 7683/0/487 0.977 R1 = 0.0515, wR2 = 0.0672 0.603 and -0.553

C58H45ClP2Ru 3 1.5CH2Cl2 1067.79 0.71073 triclinic P1 11.7631(11) 14.3743(14) 15.1703(14) 92.0960(10) 107.4580(10) 95.1120(10) 2431.8(4) 2 1.458 0.649 1094 1.41-26.00 25 037 9420 (R(int) = 0.0372) 9420/0/614 1.003 R1 = 0.0393, wR2 = 0.0892 0.840 and -0.707

C54H45ClP2Ru 3 CH2Cl2 977.29 1.54178 triclinic P1 10.4800(3) 14.2855(4) 16.7794(3) 91.329(2) 98.864(2) 111.207(2) 2305.48(10) 2 1.408 5.288 1004 2.67-67.72 23 585 8179 (R(int) = 0.0266) 8179/0/558 1.023 R1 = 0.0230, wR2 = 0.0614 0.408 and -0.496

phenanthrene), 7.43 (br, 12H, PPh3), 7.22 (m, 7H, PPh3), 7.12 (br, 11H, PPh3), 4.14 (s, 2H, CH2), 4.09 (s, 2H, Cp), 3.35 (s, 2H, Cp). 31 P{1H} NMR (161.97 MHz, CDCl3): δ 39.61 (s). Anal. Calcd for C56H45ClP2Ru 3 CH2Cl2: C, 68.37; H, 4.73. Found: C, 68.04; H, 4.90. (η5-C5H4CHPh2)RuCl(PPh3)2 (6). 6S, 130 mg, 0.564 mmol; RuHCl(PPh3)3 4.02 mg, 0.435 mmol; yield, 306 mg, 78.8%. 1H NMR (400 MHz, C6D6): δ 7.85 (d, J=6.4 Hz, 4H, Ph), 7.73 (br, 12H, PPh3), 7.30 (m, 3H, Ph), 7.16 (t, J=6.4 Hz, 3H, Ph), 7.02 (m, 18H, PPh3), 6.35 (s, 1H, CHPh2), 4.17 (s, 2H, Cp), 3.57 (s, 2H, Cp). 31P{1H} NMR (161.9 7 MHz, C6D6): δ 41.48. Anal. Calcd for C54H45ClP2Ru 3 CH2Cl2: C, 67.59; H, 4.85. Found: C, 68.7; H, 4.74. (η5-C5H4CH2cyclopentyl)RuCl(PPh3)2 (7A) and (η5-C5H4CH2cyclopentenyl)RuCl(PPh3)2 (7B). 7S, 43 mg, 0.325 mmol; RuHCl(PPh3)3, 203 mg, 0.219 mmol; yield, 106 mg, 63.9%; molar ratio of 7A to 7B=6.6:1 (based on the integrations of Cp proton signals). Characteristic 1H signals of 7A (400 MHz, CDCl3): δ 3.91 (s, 2H, Cp), 3.30 (s, 2H, Cp), 2.92 (m, 1H, CpCH of cyclopentyl), Characteristic signals of 7B (400 MHz, CDCl3): δ 5.88 (s, 1H, dCH), 4.24 (s, 2H, Cp), 3.29 (s, 2H, Cp). The 1H NMR signals of PPh3 in 7A and 7B are overlapped in the region 7.38-7.10 ppm, and other CH2 signals are overlapped in the region 2.64-1.43 ppm. 31P{1H} NMR (161.98 MHz, C6D6): 40.72 (s, 7A), 40.53 ppm (s, 7B). Anal. Calcd for C46H43ClP2Ru: C, 69.56; H, 5.46. Found: C, 69.35; H, 5.44.

(η5-C5H4-CH2cyclohexyl)RuCl(PPh3)2 (8A) and (η5-C5H4CH2cyclohexenyl)RuCl(PPh3)2 (8B). 8S, 42.6 mg, 0.29 mmol; RuHCl(PPh3)3, 216 mg, 0.234 mmol; yield, 122 mg, 64.49%; molar ratio of 8A:8B=4.52:1 (based on the integrations of Cp proton signals). Characteristic 1H signals for 8A (400 MHz, C6D6): δ 4.28 (s, 2H, Cp), 3.63 (s, 2H,Cp), 3.02 (m, 1H, CpCH of cyclohexyl). Characteristic 1H signals for 8B (400 MHz, C6D6): 6.21 (s, 1H, dCH) 4.55 (s, 2H, Cp), 3.52 (s, 2H, Cp). The 1H NMR signals of PPh3 in 8A and 8B are overlapped in the region 7.37-7.10 ppm, and other CH2 signals are overlapped in the

region 2.77-1.28 ppm 31P{1H} NMR (161.98 MHz, C6D6): 40.04 (s, 8A), 40.11 ppm (s, 8B). Anal. Calcd for C47H45ClP2Ru: C, 69.92; H, 5.49. Found: C, 69.78; H, 5.51.

(η5-C5H4-CH2cycloheptyl)RuCl(PPh3)2 (9A) and (η5-C5H4CH2cycloheptenyl)RuCl(PPh3)2 (9B). 9S, 73 mg, 0.455 mmol; RuHCl(PPh3)3, 271 mg, 0.293 mmol; yield, 150 mg, 62.4%; molar ratio of 9A:9B= 1.2:1 (based on the integrations of Cp proton signals). Characteristic 1H signals of 9A (400 MHz, C6D6): δ 4.20 (s, 2H, Cp), 3.59 (s, 2H, Cp), 3.18 (m, 1H, CpCH of cycloheptyl). Characteristic 1H signals of 9B (400 MHz, C6D6): δ 6.33 (t, J = 6.6 Hz, 1H, CdCH), 4.54 (s, 2H, Cp), 3.48 (s, 2H, Cp). The 1H NMR signals of PPh3 in 9A and 9B are overlapped in the region 7.79-7.05 ppm, and other CH2 signals are overlapped in the region 2.97-1.62 ppm. 13C{1H} NMR (100.62 MHz, CD2Cl2): δ 140.09-138.93 (m), 134.69 (virtual t, J=4.73 Hz), 129.33, 128.03 (virtual q, J=4.33 Hz) (PPh3 of 9A and 9B), 138.73, 132.19 (vinyl group of 9B), 119.35, 78.168 (t, J= 5.03 Hz), 76.25 (C5H4 of 9A), 111.45, 77.26, 77.21, 77.17 (C5H4 of 9B), 37.16, 35.55, 29.23, 26.91 (cycloheptyl group of 9A), 33.09, 32.44, 29.98, 27.61, 27.33 (cycloheptenyl group of 9B). 31 P{1H} NMR (121.5 MHz, C6D6): δ 40.34 (s, 9A), 40.61 (s, 9B). Anal. Calcd for C48H47ClP2Ru: C, 70.19; H, 5.65. Found: C, 70.39; H, 5.86.

(η5-C5H4CH2CHMe2)RuCl(PPh3)2 (10A) and [(η5-C5H4CH2CHMe2)RuCl(PPh3)2] (10B). 10S, 59 mg, 0.49 mmol; RuHCl(PPh3)3, 299 mg, 0.32 mmol; yield, 167 mg, 66.2%; molar ratio of 10A:10B=13.1:1 (based on the integration of Cp ring

Article proton signals). Characteristic 1H signals of 10A (C6D6): δ 4.24 (s, 2H, Cp), 3.58 (s, 2H, Cp), 2.66 (d, J=6.8 Hz, 2H, CpCH2), 1.85 (m, 1H, CH2CHMe2), 1.06 (d, J = 6.4 Hz, 6H, CHCH3). Characteristic 1H signals of 10B (C6D6): δ 6.42 (s, 1H, CpCHdCMe2), 4.59 (s, 2H, Cp), 3.66 (s, 2H, Cp), 0.433 (s, 6H, CMe2). The 1H NMR signals of PPh3 in 10A and 10B are overlapped in the region 7.83-7.07 ppm. 31P{1H} NMR (161.98 MHz, C6D6): δ 40.28 (s, 10A), 40.38 (s, 10B). Anal. Calcd for (4A) C45H43ClP2Ru: C, 69.09; H, 5.54. Found: C, 69.45; H, 5.63.

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at 173 and 100 K respectively. Lattice determination and data collection were carried out using SMART v.5.625 software. Data reduction and absorption correction were performed using SAINT v 6.26 and SADABS v 2.03, whereas the diffraction intensity data of 6 were collected with an Oxford Diffraction GeminiS Ultra with monochromatized Cu KR radiation (λ = 1.54178 A˚) at 173 K. Lattice determination, data collection, and reduction were carried out using CrysAlisPro 171.32.5. Absorption correction was performed using SADABS built in the CrysAlisPro program suite. Structure solution and refinement for all three compounds were performed using the SHELXTL v.6.10 software package. They were solved by the direct methods and refined by full-matrix least-squares on F2. All non-hydrogen atoms were refined anisotropically. Hydrogen atoms were introduced at their geometric positions and refined as riding atoms.

Acknowledgment. This work was supported by the Hong Kong Research Grant Council (Project No. HKUST 601306). X-ray Crystallography Studies of 2, 4, and 6. The crystals were mounted on a glass fiber, and the diffraction intensity data of 2 and 4 were collected with a Bruker Smart APEX CCD diffractometer with monochromatized Mo KR radiation (λ=0.71073 A˚)

Supporting Information Available: X-ray crystallographic files (CIF). This material is available free of charge via the Internet at http://pubs.acs.org.