Synthesis, Spectroscopy and Crystal Structure of a New Copper Complex Built Up by Cationic (Dimethylphosphoryl)methanaminium Ligands

Abstract

A new transition metal complex of the mono-protonated ligand (dimethylphosphoryl)methanamine (dpmaH+) was obtained by equimolar reaction of copper(II) chloride dihydrate and dpma in concentrated hydrochloric acid. The asymmetric unit of the title structure, [CuCl2(C3H11NOP)4][CuCl4]2, consists of one half of a fourfold charged trans-dichloridotetrakis[(dimethylphosphoryl)methanaminium]copper(II) complex with the copper atom located on an inversion centre and one tetrachloridocuprate(II) dianion found in a general position. The copper centre in the cationic complex shows a tetragonally distorted octahedral environment composed of four oxygen atoms in a square plane and two trans-coordinated chlorido ligands. This 4+2-coordination causes elongated Cu-Cl distances because of the Jahn-Teller effect. The geometry of the tetrachloridocuprate(II) dianion is best described as a seriously distorted tetrahedron. Analysis of the hydrogen bonding scheme by graph-set theory shows three patterns of rings in the title compound. The cationic copper complex reveals intramolecular hydrogen bonds between two aminium groups and the two axial chlorido ligands. Further hydrogen bonding among the cations and anions, more precisely between four aminium groups and the chlorido ligands of four adjacent tetrachloridocuprate(II) anions, lead to a chain-type structure. Comparing the coordination chemistry of the title structure with an analogue cobalt(II) compound only disclose differences in hydrogen bonding pattern resulting in an unusual chain propagation. Besides the crystal structure received spectroscopic data are in accordance with appropriate literature.