Investigation of New Coordination Modes for Coordinatively Unsaturated (Dithiolato)cobalt(III) Complex [(η⁵-Cp)Co(1,2-S₂C₂B₁₀H₁₀-S,S‘)]

A mononuclear 16-electron Cp-cobalt(III)-dithiolate complex of the general formula [( η 5 -Cp)Co(Cab S,S ‘ )] ( 2 ) (Cab S,S ‘ = 1,2-S 2 C 2 B 10 H 10 - S,S ‘ ) has been prepared by treatment of CpCo(CO)I 2 with the corresponding dilithium dithiolato ligand Li 2 Cab S,S ‘ ( 1 ). Experiments aimed at the characterization of new coordination modes for 2 are described. The reaction of 2 with BH 3 ·THF produces an unexpected bimetallic cobalt dithiolate complex, [(( η 5 -Cp)Co) 2 (Cab S,S ‘ )] ( 3 ). A second new bonding mode for 2 was generated by treatment of 2 with Lewis bases (L) to give [( η 5 -Cp)Co(Cab S,S ‘ )(L)] (L = CNBu t ( 4a ), PEt 3 ( 4b )), the 18-electron species of which consists of a mononuclear 2 coordinated through a dative Co−L bond. A third new bonding mode for 2 is illustrated by [( η 5 -Cp)Co(Cab S,S ‘ )( η 1 -CH 2 SiMe 3 - S )] ( 5 ). Reaction of 2 with (trimethylsilyl)diazomethane resulted in the formation of the alkylidene-bridged complex 5, containing a Co−C−S three-membered ring. The formation of 4 and 5 has also been investigated electrochemically. Consequently, the addition of organic and organometallic compounds into the Co−S bond of 2 has been investigated. Thus, the syntheses of half-sandwich cobalt(III) complexes [( η 5 -Cp)Co(Cab S,S ‘ )(L)] [L = η 5 -CpCo- S,S ‘ ( 3 ), η 1 -R 1 C CR 2 - S ( 6: R 1 = R 2 = COOMe ( 6a ); R 1 = H R 2 = Ph ( 6b ); R 1 = H R 2 = SiMe 3 ( 6c ))] are reported. In addition, the solid-state structures of 3, 4b, 5, and 6a were characterized by single-crystal X-ray analyses.