Tri- and tetra-meric copper(I) amides {Cu[N(SiMePh2)2]}3 and {Cu[N(SiMe2Ph)2]}4

Abstract

The compounds {Cu[N(SiMePh₂)₂]}₃1 and {Cu[N(SiMe₂Ph)₂]}₄2 have been synthesised by the reaction of CuBr with the appropriate lithium silylamide in diethyl ether solution. Both were characterized by X-ray crystallography, ¹H NMR and IR spectroscopy, and elemental analysis. They represent the first copper silylamides to be completely characterized by X-ray crystallography. Compound 1 has a very rare trimeric structure with the metals disposed in a triangular fashion and bridged by amide ligands. The less-crowded derivative 2 has an amide-bridged tetrameric structure and an almost square-planar arrangement of four coppers. The bridging amides are displaced from the Cu₄ plane such that the Cu₄N₄ core possesses a butterfly structure. In 1 the Cu ⋯ Cu and Cu–N distances average 2.481(8) and 1.976(8)Å and the corresponding distances in 2 are 2.69(3) and 1.936(6)Å. Crystal data: 1, orthorhombic, space group Pbca, a= 29.421(8), b= 18.630(4), c= 29.971(8)Å, Z= 8, R= 0.069 for 4239 [I > 3σ(I)] data; 2, triclinic, space group P, a= 15.365(3), b= 15.420(3), c= 17.797(3)Å, α= 67.58(1), β= 64.28(1), γ= 66.95(1)°, Z= 2, R= 0.050 for 10 999 [I > 2σ(I)] data.