SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF [OS6(CO)12(ETA-6-C6H6)2]

Reaction of [OsH2(CO)12]2- with [Os(eta6-C6H6)(MeCN)3][BF4]2 in CHCl2 affords the pentanuclear cluster [Os5H2(CO)12(eta6-C6H6)] which upon t reatment with 1,8-diazabicyclo[5.4.0]undec-7-ene in CH2Cl2 gives the d ianion [Os5(CO)12(eta6-C6H6)]2-, whose subsequent reaction with [Os(et a6-C6H6)(MeCN)3][BF4]2 Provides the new bis(benzene) cluster [Os6(CO)1 2(eta6-C6H6)2] in ca. 40% yield; the crystal structure of [OS6(CO)12(e ta6-C6H6)2] shows that the six osmium atoms adopt a bicapped tetrahedr al geometry with both benzene ligands in terminal eta6 sites but co-or dinated to two osmium atoms with different metal connectivities.