(Tetramethylcyclobutadiene)cobalt complexes with monoanionic carborane ligands [9-L-7,8-C2B9H10]− (L = SMe2, NMe3 and py)

nido-Carborane 9-NMe3-7,8-C2B9H11 (2c) was synthesized by CuSO4 oxidation of anion [7,8-C2B9H12]− in the presence of [Me3NH]+ in aqueous ammonia. Improved procedures for the preparation of nido-carboranes 9-SMe2-7,8-R2-7,8-C2B9H9 (2a: R = H; 2b: R = Me) and 9-py-7,8-C2B9H11 (2d) were developed. nido-Carborane monoanions [9-L-7,8-R2-7,8-C2B9H8]− (1a–1d), generated by deprotonation of 2a–2d by NaH, react with Cb*Co(CO)2I or [Cb*Co(MeCN)3]+ (Cb* = C4Me4) to give complexes Cb*Co(η-9-L-7,8-R2-7,8-C2B9H8) (3a–3d). The structures of carborane 2d and complexes 3a and 3d were determined by X-ray diffraction. Electrochemistry of the cobalt complexes was studied.