Symmetrization of Mixed-Ligand Copper(I) Complexes with Cyclic Diphosphine and ortho-Substituted Diimine Ligands

The subsequent reaction of copper(I) hexafluorophosphate with P-phenyl- and P-mesityl-substituted 1,5,3,7-diazadiphosphacyclooctanes, ortho-dimethyl-substituted bipyridine and phenanthroline leads to the formation of a mixture of cationic homoligand complexes: a bis-chelate diimine complex and a chelate diphosphine complex. With sterically loaded P-mesityl-substituted diazadiphosphacyclooctane, a trigonal P,P-chelate copper(I) complex with an acetonitrile molecule as a co-ligand is formed, whereas with P-phenyl-substituted diazadiphosphacyclooctane, a tetrahedral bis-P,P-chelate complex is formed. The recrystallisation of the latter in the aerobic conditions results in oxidation of both copper(I) ion to copper(II) and diphosphine ligands yielded a new octahedral copper(II) complex with two oxidized 3,7-dioxo-1,5,3,7-diazadiphosphacyclooctanes, which are coordinated by the copper ion with the oxygen atoms of the phosphoryl groups and the endocyclic nitrogen atom. The structure of the complexes was proven by a set of analytical methods and X-ray diffraction.