CYCLOHEXADIENE AND BENZENE-DERIVATIVES OF [RU5C(CO)15]

The reaction of [Ru5C(CO)15] 1 with cyclohexa-1,3-diene and three equivalents of Me3NO yielded the new compound [Ru5C(CO)11(eta4-C6H8)2] 2 and also [Ru5C(CO)12(mu3-eta2:eta2:eta2-C6H6)] 3 and [Ru5-C(CO)12(eta6-C6H6)] 4 in approximately equal yields. The molecular structure of 2 has been established by single-crystal X-ray diffraction. The two cyclohexadiene ligands are terminally bound on opposite basal ruthenium atoms of the square-pyramidal metal framework. Compound 2 may be converted to 3 by reaction with carbon monoxide. The isomeric pair [Ru5C(CO)10(mu3-eta2:eta2:eta2-C6H6)(mu-eta2:eta2-C6H8)] 5 and [Ru5C(CO)10(eta6-C6H6)(mu-eta2:eta2-C6H8)] 6 may be prepared from 3 and 4, respectively, upon reaction with cyclohexa-1,3-diene and two equivalents of Me3NO. Clusters 5 and 6 have also been studied by single-crystal X-ray diffraction. In both molecules the cyclohexadiene ligand bridges a basal edge of the square pyramid, while the benzene fragment is in face-capping and terminal bonding mode, respectively.