Close Correlation between Metal Oxidation States and Molecular Structures in a Cobalt–Gold Multinuclear Coordination System with Mixed D-Penicillaminate and Tripodal Triphosphine



A unique cobalt–gold coordination system, in which the oxidation states of the cobalt centers are closely correlated with the multinuclear molecular structures, is reported. This system contains a CoII3AuI6 nonanuclear structure in [Co3{Au3(tdme)(D-pen-N,O,S)3}2] ([2]) and a CoIIIAuI3 tetranuclear structure in [Co{Au3(tdme)(D-pen-N,S)3}] ([3]) [tdme = 1,1,1-tris(diphenylphosphinomethyl)ethane, D-pen = D-penicillamininate], which are stereoselectively prepared from the reaction of a tripod-type trigold(I) metalloligand [Au3(tdme)(D-pen)3]3– ([1]3–) with Co2+ and Co3+, respectively. The anomalous stability of the +II oxidation state of each octahedral cobalt center in [2], despite the coordination of two aliphatic amine and two aliphatic thiolato groups that commonly provide a strong ligand field, is notable.