Copper(I) bromide complexes from 1,2-bis(diphenylphosphano) benzene and some heterocyclic thiones

The synthesis, characterization and solid state emission properties of a series of mixed-ligand copper(I)bromide complexes containing 1,2-bis(diphenylphosphano)benzene (dppbz) and some heterocyclic thiones (L) are reported. The complexes are readily synthesized by the addition of the appropriate thione to a CuBr-diphosphane adduct in acetonitrile/methanol or acetone solution. The molecular structures of [CuBr(dppbz)(py2SH)], [CuBr(dppbz)(pymtH)] and [CuBr(dppbz)(imdtH2)] were established by single-crystal X-ray diffraction. Each of these structures features a tetrahedral copper(I) centre with two phosphorus atoms from the chelating diphos ligand, one bromine and the exocyclic sulfur atom of the heterocyclic thioamide unit. Slow decomposition of the mixed-ligand complexes via ligand dissociation occurs when their chloroform solutions are left to stand at room temperature for several weeks. On the basis of elemental analysis, NMR and IR spectra, the resulting coloured crystals are found to contain phosphane-free coordination polymers of composition [CuBr(L)]. At room temperature, some of the molecular complexes in the solid state exhibit strong emission assigned to a metal–ligand charge transfer of type Cu(I) → π*(PPh2).

Graphical abstractThe behaviour of the diphos ligand 1,2-bis(diphenylphosphano)benzene (dppbz) towards coordination of CuBr in the presence of several heterocyclic thione ligands has been investigated. The diphos ligand acts as a chelating ligand whereby the thiones are terminally bound through the exocyclic sulfur atom, leading to the formation of monomeric complexes of type [CuBr(dppbz)L]. The crystal structures of three examples of the novel complexes have been characterized by X-ray crystallography.Figure optionsDownload full-size imageDownload as PowerPoint slide