Synthesis, crystal structure and Raman spectra of [dabcoH2]CuICl3, [dabcoH2]3Cl4CuIICl4(DMSO) and Cu3Cl3(dabco)(DMSO) (dabco = 1,4-diazabicyclo [2.2.2] octane)

Abstract

Dissolving elemental copper in a CCl4–DMSO mixture in the presence of dabco (dabco = 1,4-diazabicyclo [2.2.2] octane) resulted in the formation of a compound with the composition [dabcoH2][CuCl3] featuring a univalent copper salt. This compound, composed of discrete dabcoH22+ cations and CuCl32− anions, represents the first example of a copper(I) chloride derivative containing a doubly protonated [dabcoH2]2+ unit, and a very rare example of the oxidative dissolving of copper in a CCl4–DMSO mixture to give a Cu(I) compound. The addition of some drops of water to the initial reaction mixture led to the formation of the [dabcoH2]3Cl4CuCl4(DMSO). Three [dabcoH2]2+ units and four Cl− anions, bound via N–H…Cl hydrogen bonds, form a horseshoe-like cationic fragment. The divalent copper ion possesses a rather unusual pseudo-tetrahedral surrounding. The comproportionation reaction of CuCl2·2H2O and copper powder in the presence of dabco in DMSO results in the formation of the Cu3Cl3(dabco)(DMSO) complex. Copper and chlorine ions form unprecedented Cu6Cl6 cores, interconnected by neutral dabco linkers into infinite 2-D layers. All the compounds were characterized using the single-crystal X-ray diffraction technique and Raman spectroscopy.