Synthesis and molecular structures of the dicobalt carbonylphosphine pi-complexes containing acetylene with functional groups CH2OH and CH2SCMe3

The replacement of one or two OH groups in [Co-2(CO)(6)][mu-C-2(CH2OH)(2)] (I) by SCMe3 in the presence of HBF4 gave the corresponding pi-complexes wi th thiolate-substituted acetylene, which were isolated as [(Ph3P)Co-2(CO)(5 )][mu-C-2(CH2SCMe3)(2)] (II) and [(Ph3P)Co-2(CO)(5)][mu-C-2(CH2SCMe3)(CH2OH )] (III) single crystals after substituting PPh3 for one CO group. The stru ctures of II and III were determined by X-ray structural analysis. The geom etry of the Co-2(CH2C=CCH2) core was shown to weakly depend on the nature o f substituents at the cobalt atoms, carbon atoms of the methylene groups, o r sulfur atoms. It is suggested that the formal electron deficiency at the metal atoms pi-coordinated by the triple C=C bond has the decisive effect o n the core geometry.