Preparation and study of three-coordinate mixed ligand copper(I) compounds. Molecular and crystal structure of (tricyclohexylphosphine)(2-thioxohexamethyleneimine)copper(I) iodide

Abstract A group of mixed ligand copper(I) coordination compounds with the saturated heterocyclic thione 2-thioxohexamethyleneimine ( w -thiocaprolactam, tclH) and tricyclohexylphosphine (Pcy 3 ) is prepared and studied. The concerted steric effects of the two bulky ligands result in the formation of three-coordinate copper(I) complexes. The iodo compound is studied by single crystal X-ray diffraction and is shown to crystallize in the P 2 1 / n space group. Four monomer units with no apparent close contacts between them are present in the unit cell, the dimensions of which area a =10.306(2), b =15.937(2), c =16.774(2) A, and β=100.06(1) o . The compound is trigonal planar with the CuS, CuP and CuI bonds equal to 2.243(2), 2.241(2) and 2.564(1) A, respectively. A computational study is also carried out aiming at the understanding of the factors influencing planar or pyramidal conformation in three-coordinate CuLL′L″ compounds.