Syntheses of some organogoldtriosmium clusters; X-ray crystal structure of [Os3(CO)8(PPh3){Au(PPh3)}(2-NHC5H4N)

Abstract

The clusters [Os3(CO)9{Au(PPh3)}(C2Ph)](1), [Os3(CO)10{Au(PPh3)}(OH)](2), [Os3(CO)10{Au(PPh3)}(NHSO2C6H4Me-p)](3), and [Os3(CO)8(Y){Au(PPh3)}(2-NHC5H4N)][Y = PPh3(4) or CO (5)] were prepared from the appropriate neutral osmium cluster and chloro(triphenylphosphine)gold(I). [Os3(CO)8(PPh3){Au(PPh3)}(2-NHC5H4N)](4) was shown by X-ray analysis to consist of an isosceles triangle of osmium atoms substituted by an equatorial phosphine ligand and eight carbonyls. A 2-pyridylamido ligand caps one side of the Os3 triangle and a (triphenylphosphine)aurio group bridges the longest Os–Os bond. The complex crystallises in space group P21/n with a= 14.567(5), b= 18.010(24), c= 18.456(7)Å, β= 92.22(3)°, and Z= 4. The structure was solved by a combination of direct methods and Fourier-difference techniques, and refined by blocked-cascade least-squares methods to R= 0.065 to 3 541 observed diffractometer data.