Synthesis of Heterometal Cluster Complexes by the Reaction of Cobaltadichalcogenolato Complexes with Groups 6 and 8 Metal Carbonyls Masaki Murata, Satoru Habe, Shingo Araki, Kosuke Namiki, Teppei Yamada, Norikiyo Nakagawa, Takuya Nankawa, Masayuki Nihei, Jun Mizutani, Masato Kurihara, and Hiroshi Nishihara* Department of Chemistry, School of Science, The UniVersity of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Received August 4, 2005 Metalladichalcogenolate cluster complexes [{CpCo(S 2 C 6 H 4 )} 2 Mo(CO) 2 ] (Cp ) η 5 -C 5 H 5 )(3), [{CpCo(S 2 C 6 H 4 )} 2 W- (CO) 2 ](4), [CpCo(S 2 C 6 H 4 )Fe(CO) 3 ](5), [CpCo(S 2 C 6 H 4 )Ru(CO) 2 (P t Bu 3 )] (6), [{CpCo(Se 2 C 6 H 4 )} 2 Mo(CO) 2 ](7), and [{CpCo(Se 2 C 6 H 4 )}(Se 2 C 6 H 4 )W(CO) 2 ](8) were synthesized by the reaction of [CpCo(E 2 C 6 H 4 )] (E ) S, Se) with [M(CO) 3 (py) 3 ] (M ) Mo, W), [Fe(CO) 5 ], or [Ru(CO) 3 (P t Bu 3 ) 2 ], and their crystal structures and physical properties were investigated. In the series of trinuclear group 6 metal-Co complexes, 3, 4, and 7 have similar structures, but the W-Se complex, 8, eliminates one cobalt atom and one cyclopentadienyl group from the sulfur analogue, 4, and does not satisfy the 18-electron rule. 1 H NMR observation suggested that the CoW dinuclear complex 8 was generated via a trinuclear Co 2 W complex, with a structure comparable to 7. The trinuclear cluster complexes, 3, 4, and 7, undergo quasi-reversible two-step one-electron reduction, indicating the formation of mixed-valence complexes Co III M 0 Co II (M ) Mo, W). The thermodynamic stability of the mixed-valence state increases in the order 4 < 3 < 7. In the dinuclear group 8 metal-Co complexes, 5 and 6, the CpCo(S 2 C 6 H 4 ) moiety and the metal carbonyl moiety act as a Lewis acid character and a base character, respectively, as determined by their spectrochemical and redox properties. Complex 5 undergoes reversible two-step one-electron reduction, and an electron paramagnetic resonance (EPR) study indicates the stepwise reduction process from Co III Fe 0 to form Co III Fe -I and Co II Fe -I . Introduction Metalladichalcogenolenes of late transition metals exhibit unique electronic properties due to their quasi-aromaticity caused by strong dπ-pπ interaction, in which the metal center can be stabilized in unsaturated 16e - forms by the contribution of lone pair electrons in chalcogen (S, Se) atoms. 1 This electron deficiency of the metal center suggests the possibility of utilizing mononuclear metalladichalco- genolenes as building blocks of metal cluster complexes. In an exploration of this idea, we found a first example of a metal-metal bond formation of metalladithiolene complex; a reaction of [CpCo(S 2 C 6 H 4 )] (1) with [Mo(CO) 3 (py) 3 ] produced a trinuclear cluster complex [{CpCo(S 2 C 6 H 4 )} 2 - Mo(CO) 2 ](3) as reported in a communication. 2 This complex possesses a slightly bent Co-Mo-Co bond and extremely crooked cobaltadithiolene rings, indicating molecular orbital delocalization not only on the Co-Mo-Co bond but also on the metal-S bonds. This leads to thermal stability, the appearance of lower energy absorption bands in a VIS spectrum, and a reversible redox response. 2 We also syn- thesized the metalladiselenolene cluster complex, [CpCo- (Se 2 C 6 H 4 )] 2 (2), 3 which can be one of starting materials for this series of cluster complexes. It should be noted that Jin et al. have studied similar metal-metal bond formation reactions of carborane-dichalcogenolene complexes. 4 In this study, we investigated the reactions of 1 and 2 with groups * To whom correspondence should be addressed. E-mail: nisihara@ chem.s.u-tokyo.ac.jp. Tel: +81 3 5841 4346. Fax: +81 5841 8063. (1) (a) McCleverty, J. A. Prog. Inorg. Chem. 1969, 2, 72. (b) Eisenberg, R. Prog. Inorg. Chem. 1970, 12, 295. (c) Burns, R. P.; McAullife, C. A. AdV. Inorg. Chem. Radiochem. 1979, 22, 303. (d) Fourmigue, M. Coord. Chem. ReV. 1998, 178-180, 823. (e) Sugimori, A.; Akiyama, T.; Kajitani, M.; Sugiyama, T. Bull. Chem. Soc. Jpn. 1999, 72, 879. (2) Nihei, M.; Nankawa, T.; Kurihara, M.; Nishihara, H. Angew. Chem., Int. Ed. 1999, 38, 1098. (3) Habe, S.; Yamada, T.; Nankawa, T.; Mizutani, J.; Murata, M.; Nishihara, H. Inorg. Chem. 2003, 42, 1952. Inorg. Chem. 2006, 45, 1108-1116 1108 Inorganic Chemistry, Vol. 45, No. 3, 2006 10.1021/ic0513282 CCC: $33.50 © 2006 American Chemical Society Published on Web 01/04/2006