A substituted hexaosmium hydrido cluster with benzene ligands in two different bonding modes; synthesis and structural characterisation of [Os6H2(CO)11(η6-C6H6)(µ3-η2:η2:η2-C6H6)]

Abstract

Treatment of [Os₅H₄(CO)₁₁(η⁶-C₆H₆)]1 with 1,8-diazabicyclo[5.4.0]undec-7-ene in CH₂Cl₂ gives the dianion [Os₅H₂(CO)₁₁(η⁶-C₆H₆)]^2–2, and subsequent reaction of 2 with [Os(η⁶-C₆H₆)(MeCN)₃][BF₄]₂ provides the new bis-benzene cluster [Os₆H₂(CO)₁₁(η⁶-C₆H₆)(µ₃-η²:η²:η²-C₆H₆)]3 in ca. 35% yield, the X-ray analysis of which shows that the six osmium atoms adopt a bicapped tetrahedral geometry with one benzene ligand in a terminal η⁶ site and the other in a face-capping µ₃-η²:η²:η² site.