Copper(I) bromide and chloride complexes with urotropine and triethylenediamine: synthesis, crystal structure, and Raman characterization

In the present study, the oxidative dissolution of metallic copper has been explored with the intention to prepare some new complexes with urotropine (hmta) and triethylenediamine (dabco) ligands. All the compounds synthesized were characterized by single-crystal X-ray diffraction and Raman spectroscopy. Reactions performed in a DMSO/CuCl2∙2H2O mixture resulted in [(μ-Cl)2CuI(hdabco+)CuI(μ-Cl)(κS-DMSO)]n and [CuICl(hmta)2] complexes. Their isostructural bromide analogs [(μ-Br)2CuI(hdabco+)CuI(μ-Br)(κS-DMSO)]n and [CuIBr(hmta)2] were prepared by the reaction of elemental copper with respective ligands in a DMSO/CBr4 mixture. Early interrupted reaction of the copper wire with the DMSO/CBr4/dabco solution resulted in an appearance of crystals of the [CuI2Br2(CO)2(dabco)]n carbonyl complex on the copper surface. It arises with the participation of in situ formed carbon monoxide. Despite the identical stoichiometry, the crystal structure of the [Cu2Br2(CO)2(dabco)]n complex is markedly different from that of a known [Cu2Cl2(CO)2(dabco)]n analog.