CRYSTAL-STRUCTURE OF [CU-4(TU)(7)](SO4)(2)]CENTER-DOT-H2O AND VIBRATIONAL SPECTROSCOPIC STUDIES OF SOME COPPER(I) THIOUREA COMPLEXES

The complex [Cu-4(tu)(7)](SO4)(2) . H2O was isolated by addition of th iourea to a copper(II) sulfate electrolyte solution consisting of 2 M H2SO4 and 0.7 M CuSO4. The crystal structure of this complex was solve d by X-ray methods and highlighted a [Cu-4(tu)(7)](4+) adamantane clus ter. A copper(I)-thiourea cluster of this stoichiometry has not been p reviously reported. The X-ray structure is refined to residual R = 0.0 447 for 4093 observed reflections. Crystals are orthorhombic, of space group Pbca, with Z = 8 in a cell of dimensions a = 10.414(3), b = 17. 909(3), and c = 35.818(3) Angstrom. The copper atoms lie in a tetrahed ral arrangement in which one of the copper atoms is four-coordinate, w hile the other three display trigonal planar coordination with Cu...Cu distances of 2.899(2)-2.967(2)Angstrom. The copper-thiourea clusters are interlinked by sulfate ions, which strongly interact with the thio urea ligands through hydrogen bonds. The infrared and Raman spectra of the title compound and of the related copper(I) thiourea complexes [C u-2(tu)(5)](SO4). 3H(2)O, [Cu-2(tu)(6)](SO4). H2O, [Cu-4(tu)(6)](NO3)( 4) . 4H(2)O, and [Cu-4(tu)(9)](NO3)(4) . H2O were recorded and assigne d, and the dependence of v(CuS) on the coordination environment of the copper was established.