Synthesis and X-ray crystal structures of dimeric nickel(0) and tetrameric copper(I) iodide complexes of 2-diphenylphosphino-3-methylphosphinine

Abstract

The dimer [Ni 2(μ-CO)(CO) 2(μ- 1) 2] 2 has been prepared by two different procedures which involve the reaction of the 2-diphenyl-phosphino-3-methylphosphinine ligand 1 with either Ni(COD) 2 or NiBr 2 · DME/Zn under CO atmosphere. The crystal structure of 2 has been determined by X-ray crystallography. As the analogous dppm complex, 2 adopts a W-frame structure with two bridging ligands 1, two terminal carbonyl ligands and one bridging carbonyl ligand. An electrochemical study reveals that the electron density in the Ni 2 core is considerably reduced in 2 compared to the dppm complex. The reaction of 1 with two equivalents of copper iodide yields the tetranuclear complex [Cu 4(μ-I) 2(μ 4-I) 2(μ- 1) 2] 3 which has been identified by an X-ray diffraction study. The structure of 3 consists of an octahedron having a square planar Cu 4 base bridged by two ligands 1 and two μ 2-iodo atoms. The most surprising feature of this structure concerns the coordination of the two other iodide atoms respectively located at each apex of the octahedron, which display a face μ 4-face-bridging bonding mode.