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.