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

The reaction of Os3(CO)10(NCMe)2 (1) with C6H5Au­(PPh3) has yielded the complex Os3(CO)10(μ,η1-C6H5)­(μ-AuPPh3) (2), which contains an bridging η1-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 °C), compound 2 was decarbonylated and converted to the complex Os3(CO)9(μ3-C6H4)­(μ-AuPPh3)­(μ-H) (3), which contains a triply bridging benzyne ligand by a CH cleavage on the bridging phenyl ring. The reaction of Os3(CO)10(NCMe)2 with (1-C10H7)­Au­(PPh3) (1-C10H7 = 1-naphthyl) yielded the complex Os3(CO)10(μ-2-C10H7)­(μ-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 η1-2-naphthyl ligand and a bridging Au­(PPh3) group and is electronically unsaturated overall. The pink isomer 4b contains a bridging η2-2-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 Os3(CO)9(μ3-C10H6)­(μ-AuPPh3)­(μ-H) (5) when heated to reflux in octane (125 °C) for 30 min. Compound 5 contains a triply bridging 1,2-naphthyne ligand.