Synthesis of Copper(I) Complexes with Ketimide and Hydrazide Ligands

Copper(I) chloride reacted with lithium ketimides to form tetrameric homoleptic copper(I) ketimide complexes, [Cu(N=CR₂)]₄, where R = t-Bu or Ph. Mesityl copper reacted with excess 1-trimethylsilylmethyl-2,2,-dimethylhydrazine to give the mixed ligand complex (2,4,6-C₆Me₃H₂)Cu₄[N(SiMe₃)NMe₂]₃. Single-crystal X-ray crystallographic studies revealed that the three complexes have eight-member ring structures in which the ring has a hinged or butterfly shape. Although an eight-member ring structure is common for copper(I) amido, alkyl, and aryl clusters, the structure of [Cu(N=C-t-Bu₂)]₄ is unusual because the hinge angle is significantly smaller than is common, resulting in short Cu···Cu contacts compared to related complexes.