Linking thione-ligated copper(I) centres with trans-1,2-bis(diphenylphosphino)ethene (trans-dppen): crystal structures of the pyrimidine-2-thione derivatives [CuBr(μ2-trans-dppen)(pymtH)]2 and [CuI(μ2-trans-dppen)(pymtH)]2

The behaviour of the diphos ligand trans-1,2-bis (diphenylphosphino)ethene (trans-dppen) towards coordination of CuX [X = Br, I] in the presence of several heterocyclic thione ligands has been investigated. The diphos ligand adopts the doubly-bridging coordination mode whereby the thiones are terminally bound through the exocyclic sulfur atom, leading to the formation of homobimetallic complexes of type [CuX(μ2-trans-dppen)L]2. The crystal structures of two examples of the novel complexes have been characterized by X-ray crystallography.