Synthesis and Transformations of Triosmium Carbonyl Cluster Complexes Containing Bridging Aryl Ligands

The reaction of Os-3(CO)(10)(NCMe)(2) (1) with C6H5Au(PPh3) has yielded the complex Os-3(CO)(10)(mu,eta(1)-C6H5)(mu-AuPPh3) (2), which contains an bridging eta(1)-phenyl ligand and a Au(PPh3) group that bridges the same unsaturated Os-Os bond in the 46-electron cluster complex. When it was heated to reflux in an octane solution (125 degrees C), compound 2 was decarbonylated and converted to the complex Os-3(CO)(9)(mu(3)-C6H4)(mu-AuPPh3)(mu-H) (3), which contains a triply bridging benzyne ligand by a CH cleavage on the bridging phenyl ring. The reaction of Os-3(CO)(10)(NCMe)(2) with (1-C10H7)Au(PPh3) (1-C10H7 = 1-naphthyl) yielded the complex Os-3(CO)(10)(mu-2-C10H7)(mu-AuPPh3) (4), which exists as two isomeric forms in the solid state. A 1,2-hydrogen shift in the naphthyl ligand occurred in the formation of 4. The green isomer 4a is structurally similar to 2 and contains a bridging eta(1)-2-naphthyl ligand and a bridging Au(PPh3) group and is electronically unsaturated overall. The pink isomer 4b contains a bridging eta(2)-2-naphthyl ligand and a bridging Au(PPh3) group and is electronically saturated. The pink isomer is found in hexane solution and was converted to the complex Os-3(CO)(9)(mu(3)-C10H6)(mu-AuPPh3)(mu-H) (5) when heated to reflux in octane (125 degrees C) for 30 min. Compound 5 contains a triply bridging 1,2-naphthyne ligand.