Synthesis and molecular structure of pi-acetylene tetracobaltdecacarbonyl butterfly clusters [(CO)(8)Co-4(mu-CO)(2)](mu-C2R2), where R = CH2OH or CH2SCMe3

The tetranuclear clusters [(CO)(8)Co-4(mu-CO)(2)](mu-C2R2), where R = CH2OH or CH2SCMe3, were prepared by the reaction of Co-2(CO)(8) with [Co-2(CO)(6 )][mu-C-2(CH2OH)(2)] in CH2Cl2 or with [CO2(CO)(6)][mu-C-2(CH2SCMe3)(2)] in hexane. According to the X-ray diffraction data, they contain the butterfl y metal core. The acetylene carbon atoms (C drop C 1.420(6) or 1.421(5) Ang strom, respectively) are bonded to all cobalt atoms, and the C C drop C ang les are decreased to 125 degrees on average, which results in the formation of the intramolecular hydrogen bond in the case of R = CH2OH.