Mixed alkyne-arene-substituted carbonyl clusters; the crystal and molecular structure of OS 4(CO) 9(η 6-C 6H 6)(MeCCMe)

Abstract

Reaction of the alkyne-substituted cluster anion [Os 3(CO) 9(R 1CCR 2)] 2− with the cation [Os(η 6-C 6H 6)(CH 3CN)] 2+ affords the neutral tetranuclear cluster Os 4(CO) 9(η 6-C 6H 6)(R 1CCR 2) (R 1=R 2=Me ( 1a); R 1=Me, R 2=Ph ( 1b); R 1=R 2=Ph ( 1c)). The structure of 1a has been confirmed by a single-crystal X-ray analysis. The metals adopt a ‘butterfly’ geometry with the alkylenic CC vector parallel to the ‘hinge’ vector of the ‘butterfly’, and the η 6-C 6H 6 ligand occupies a terminal site on one of the ‘wingtip’ Os atoms. Complexes 1a and 1b may also be prepared by the reaction of the activated arene cluster Os 4H 2(CO) 9(η 6-C 6H 6)(CH 3CN) with MeCCMe and MeCCPh, respectively. Under similar reaction conditions, with PhCCPh, the arene and acetonitrile ligands are substituted by the alkyne to give the known complex Os 4H 2(CO) 9(PhCCPh) 2 ( 2c).