Reactions of [Os3(µ-H)2(CO)10] with diazo-compounds: structural characterization of [Os3(µ-H)(CO)10(µ-NHNCPh2)] and [Os3(µ-H)(CO)10(µ-NHNCPhMe)]

Abstract

The unsaturated cluster [OS₃H₂(CO)₁₀] reacts with diazo-compounds N₂CR¹R² to give complexes of the form [OS₃(µ-H)(CO)₁₀(µ-NHNCR¹R²)][R¹= R²= Ph(1); R^l= Ph, R²= Me(2); R¹= Ph, R²= H(3); and R¹= R²= Me(4)]. Compound (4) reverts to [Os₃H₂(CO)₁₀] in solution at 20 °C; a mechanism for the decomposition of complex (4) is proposed. Complexes (1)–(3) are stable in solution and the structures of [Os₃(µ-H)(CO)₁₀(µ-NHNCPh₂)](1) and [Os₃(µ-H)(CO)₁₀(µ-NHNCPhMe)](2) in the solid state have been confirmed by single-crystal X-ray analyses. Both complexes crystallise in the monoclinic space group P2₁/c with Z= 4, and a= 13.645(7), b= 11.948(8), c= 16.784(11)Å, β= 101.36(3)° for (1) and a= 17.020(8), b= 9.181(3), c= 16.594(7), Å, and β= 113.70(2)° for (2). The structures have been solved by a combination of direct methods and Fourier techniques, and refined by blocked full-matrix least squares to R= 0.079 for 2 712 observed intensities (1) and R= 0.050 for 2 375 intensities (2). In both structures the Os atoms define an isosceles triangle the short edge of which is bridged by an N atom of the NHNCR¹R² ligand and by the hydride. Spectroscopic data for (2) indicate the presence of two isomers in solution.