Electrochemical behavior of the Cp*(dithiolato)Co(III) complex [(η 5-Cp*)Co(1,2-S 2C 2B 10H 10- S, S′)] and its derivatives: the effect of the ligand on half-sandwich cobalt(III) complexes

Abstract

Reaction of the 16-electron dithiolatocobalt, [(η 5-Cp*)Co(Cab S, S′ )] ( 1) (Cab S, S′ =1,2-S 2C 2B 10H 10- S, S′), with a ligand L (L=CN t Bu, PMe 3, PEt 3, PHPh 2) affords the 18-electron complexes [(η 5-Cp*)Co(Cab S, S′ )(L)] ( 2) in high yield. The structures of 2 in solution were probed by NMR spectroscopy, and the solid-state structure of the diphenylphosphine derivative was established by single-crystal X-ray diffraction. Cyclic voltammetry of 1 shows that the complex undergoes a quasi-reversible one-electron oxidation and reversible reduction. The voltammetry of the corresponding 18-electron complex 2 was investigated rather extensively in terms of coordination and redox chemistry, in which the influence of the enhanced steric interaction between the bulky Cp* and incoming ligand could be observed. Cyclic voltammograms of alkylidiene or acetylene adducts of dithiolatocobalt complex 1, [(η 5-Cp*)Co{η 3-( S, S′, C′)-SC 2B 10H 10S(C′R 2)}] [C′R 2=CHSiMe 3 ( 3a), HCCPh ( 3b), (COOMe)CC(COOMe) ( 3c)], are also included.