Structure of Halogenophosphorincopper(I) Complexes in Solid State and Solution: Study with X-ray Crystallography and CP/MAS- 31P{ 1H}-NMR Spectroscopy

Abstract

Halogenophosphorincopper(I) complexes [Cu(dmppn)X] (X=Cl ( 1), Br ( 2), I ( 3)) have been synthesized from 4,5-dimethyl-2-phenylphosphorin (dmppn) with copper(I) halide CuX (X=Cl, I) or copper(II) dihalide CuX 2 (X=Cl, Br). The crystal structure of 3 was determined by single crystal X-ray crystallography and showed supramolecular structure so called an infinite stair polymer. This complex is the only one for the infinite stair polymer of halogenocopper(I) complex with phosphorus ligand to the best of our knowledge. The chemical shifts for these complexes were observed to be 159.3( 1), 158.1( 2), and 151.2 ppm( 3) by CP/MAS– 31P{ 1H} NMR spectroscopy in the solid state and they showed significant upfield shifts over 20 ppm relative to that of the free ligand in CDCl 3. These upfield shifts indicate that the phosphorin undergoes strong π-back donation from the copper(I) center and the magnitudes of the upfield shifts for the complexes showed an obvious increase in order of I>Br>Cl. This trend indicates that degree of the π-back donation is influenced by the donor character of the halogeno ligand through the copper–halogen bonding. The copper center in these complexes was further determined to have a four-coordination in a distorted tetrahedron with CP/MAS– 31P{ 1H}–NMR data and this result suggests that three complexes were formed the supramolecular structure of the infinite stair polymer in the solid state.