Polynuclear carbonyl complexes of cobalt containing isocyanides and other ligands

Abstract

Isocyanides, RNC (R = alkyl but usually Me or Bu^t), displace up to five carbonyl ligands from [Co₄(CO)₁₂], [(π-C₅H₅)NiCo₃(CO)₉], [YCCo₃(CO)₉](Y = Cl, Me, or Ph), [SCo₃(CO)₉], and [SCo₂Fe(CO)₉]. The reactions usually take place under mild conditions with retention of the pseudotetrahedral XCo₃ or SCo₂Fe cluster (X = Co, Ni, C, or S). With octacarbonyldicobalt, the products are derivatives of [Co₄(CO)₁₂] or [(RNC)₅Co][Co(CO)₄], but never of [Co₂(CO)₈]. [{LCo(CO)₃}₂Hg](L = tertiary phosphine or CO) and [(R₃P)₂Co(CO)₃][Co(CO)₄] salts undergo similar CO replacement reactions. The structures of the products are discussed on the bases of their i.r. spectra.