Molecular structure of tetrakis(tert-butylimido)osmium(VIII), determined in the gas phase by electron diffraction

Abstract

The molecular structure of Os(NBu^t)₄ has been determined in the gas phase by electron diffraction. The NBu^t groups are in a distorted-tetrahedral arrangement around the central osmium atom, and bent in such a way that the overall molecular symmetry is reduced to S₄. The Os–N bond length (r_a) is 175.0(3) pm, and Os–N–C is 156.4(15)°. Two of the N–Os–N angles (about the S₄ axis) are 104.6(14)° and the other four are 111.9(7)°. Other important parameters are r(N–C) 147.6(9), r(C–C) 1 52.7(4) pm and N–C–C 107.0(5)°. Geometrical parameters for Os(NMe)₄ and Os(NH)₄ optimised using density functional theory are presented, and interpreted with the aid of extended-Hückel calculations.