Thioether-Functionalized Ferrocenyl-bis(phosphonite), Fe{(C 5 H 4 )P(-OC 10 H 6 (μ-S)C 10 H 6 O-)} 2 : Synthesis, Coordination Behavior, and Application in Suzuki-Miyaura Cross-Coupling Reactions Benudhar Punji, † Joel T. Mague, ‡ and Maravanji S. Balakrishna* ,† Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India, Department of Chemistry, Tulane UniVersity, New Orleans, Louisiana 70118 Received August 2, 2007 The thioether-functionalized metalloligand ferrocenyl-bis(phosphonite), Fe(C 5 H 4 PR) 2 (4,R ) -OC 10 H 6 (µ-S)C 10 H 6 O-) is synthesized in three steps starting from ferrocene, and its coordination behavior toward various transition-metal derivatives is described. The reactions of 4 with [Rh(CO) 2 Cl] 2 or M(COD)Cl 2 afforded the chelate complexes, cis- [Rh(CO)Cl{Fe(C 5 H 4 PR) 2 -κP,κP}](5) or cis-[MCl 2 {Fe(C 5 H 4 PR) 2 -κP,κP}](6,M ) Pd II ; 7,M ) Pt II ), respectively. However, treatment of 4 with CuX (X ) Cl, Br, and I) produces binuclear complexes, [Cu 2 (µ-X) 2 (MeCN){Fe(C 5 H 4 - PR) 2 -κP,κP}](8,X ) Cl; 9,X ) Br; 10,X ) I) where the sulfur atom on one side of the ligand is involved in a weak interaction with the copper center. Reaction of 4 with 1 equiv of Ag(PPh 3 )OTf gives the mononuclear chelate complex [Ag(OTf)PPh 3 {Fe(C 5 H 4 PR) 2 -κP,κP}](11), whereas treatment with 2 equiv of AuCl(SMe 2 ) produces the dinuclear gold complex [Au(Cl){Fe(C 5 H 4 PR) 2 -κP,κP}Au(Cl)] (12). The crystal structures of 10 and 12 are reported, where a strong metallophilic interaction is observed between the closed-shell metal centers. The palladium complex 6 catalyzes the Suzuki cross-coupling reactions of aryl bromides with phenylboronic acid with excellent turnover numbers (TON up to 1.36 × 10 5 ). Introduction Metal-containing ligands, particularly those based on the ferrocene scaffold, have played important roles in catalysis and material science 1 and also in medicinal applications. 2 Ferrocenyl-phosphine ligands are able to form complexes with transition metals in a variety of coordination geometries and oxidation states, which have proven to be efficient catalysts for many organic transformations. 3 Several ferro- cenyl-phosphines such as monophosphines, 4 diphosphines (1,1′-, 1,2-, 1,3-disubstitution), 5 polyphosphines 6 with dif- ferent steric and electronic properties, and also chiral ferrocenyl ligands 7 have been well-studied and have shown good catalyst activity. In contrast, the readily modifiable ferrocenyl-phosphonite or -phosphite derivatives have been much-less explored although they offer an attractive alterna- tive to ferrocenyl-phosphine ligands. Recently, Reetz and co- workers and Pastor and co-workers have reported 8 the * To whom correspondence should be addressed. E-mail: krishna@ chem.iitb.ac.in, Tel.: + 91 22 2576 7181, Fax: + 91 22 2576 7152/2572 3480. † Indian Institute of Technology Bombay. ‡ Tulane University. (1) (a) Togni, A.; Hayashi, T. Ferrocenes: Homogeneous Catalysis- Organic Synthesis-Materials Science; VCH Publishers: Weinheim, Germany, 1995. (b) Togni, A.; Halterman, R. L. Metallocenes; Wiley- VCH: Weinheim, Germany, 1998. (c) Long, N. J. Metallocenes: An Introduction to Sandwich Complexes; Blackwell Science: Oxford, U.K., 1998. (d) Atkinson, R. C. J.; Gibson, V. C.; Long, N. J. Chem. Soc. ReV. 2004, 33, 313-328. (e) Schwink, L.; Knochel, P. Chem.s Eur. J. 1998, 4, 950-968. (2) (a) Viotte, M.; Gautheron, B.; Nifant’ev, I.; Kuz’mina, L. G. Inorg. Chim. Acta 1996, 253, 71-76. (b) Rawls, R. Chem. Eng. News 1986, 21. (3) (a) Colacot, T. J. Chem. ReV. 2003, 103, 3101-3118. (b) Barbaro, P.; Bianchini, C.; Giambastiani, G.; Parisel, S. L. Coord. Chem. ReV. 2004, 248, 2131-2150. (4) (a) S ˇ te ˇpnic ˇka, P.; Cı ´sar ˇova ´, I.; Gyepes, R. Eur. J. Inorg. Chem. 2006, 926-938. (b) S ˇ te ˇpnic ˇka, P. Eur. J. Inorg. Chem. 2005, 3787-3803. (c) Richards, C. J.; Mulvaney, A. W. Tetrahedron: Asymmetry 1996, 7, 1419-1430. (5) For example see: (a) Gusev, O. V.; Peganova, T. A.; Kalsin, A. M.; Vologdin, N. V.; Petrovskii, P. V.; Lyssenko, K. A.; Tsvetkov, A. V.; Beletskaya, I. P. Organometallics 2006, 25, 2750-2760. (b) Lee, S.; Koh, J. H.; Park, J. J. Organomet. Chem. 2001, 637-639, 99- 106. (c) Butler, I. R.; Drew, M. G. B.; Greenwell, C. H.; Lewis, E.; Plath, M.; Mussig, S.; Szewczyk, J. Inorg. Chem. Commun. 1999, 2, 576-580. (d) Boyes, A. L.; Butler, I. R.; Quayle, S. C. Tetrahedron Lett. 1998, 39, 7763-7766. (e) Hayashi, T.; Yamamoto, A.; Hojo, M.; Ito, Y. J. Chem. Soc., Chem. Commun. 1989, 495-496. Inorg. Chem. 2007, 46, 10268-10275 10268 Inorganic Chemistry, Vol. 46, No. 24, 2007 10.1021/ic701537k CCC: $37.00 © 2007 American Chemical Society Published on Web 10/19/2007