Lewis-Base Adducts of Group 11 Metal(I) Compounds. XLII : [Cu4X4L4] 'cubane' clusters, L = hindered N-base ligand: synthesis and structures of the L = 2-(diphenymethyl)pyridine complexes (X = Cl, Br, I)

Abstract

The synthesis and single-crystal X-ray structure characterization of tetrameric cubane clusters of copper(1) halides with the hindered N-base ligand 2-(diphenylmethy1)pyridine are reported. The chloride, bromide and iodide structures are isomorphous , crystallizing in the tetragonal space group 141/a, a 蠲3, c 蠱2 Š, Z = 4 tetramers, the tetramer having crystallographically imposed 4 symmetry, well removed from the ideal 43m. In terms of each X3CuN fragment of the core, this distortion results in one of the N-Cu-X angles being enlarged by c. 30꠷ith respect to the other two and one Cu-X bond distance shortened. Cu-N is also shorter than is usual in a four-coordinate environment and the cluster can be envisaged as being constructed from four quasi-linear monomers. The distortions may be attributed to interaction between the 6- and 2-a-substituent-hydrogen atoms and the halide atoms of the core. The effect diminishes with increasing halide size and increasing volume of the Cu4X4 core.