A.E. Bolzán

X-ray diffraction study of copper(I) thiourea complexes formed in sulfate-containing acid ­solutions

The formation of three different copper(I) thiourea complexes in sulfate-containing acid solutions was observed. The ratio between Cu(I) and thiourea (tu) in these complexes depends on the amount of thiourea and copper sulfate in the solution. The crystal and molecular structure of a new complex, [Cu(2)(tu)(6)](SO(4)).H(2)O, was determined, and the formation and structures of [Cu(2)(tu)(5)](SO(4)).3H(2)O and [Cu(4)(tu)(7)](SO(4))(2).H(2)O were confirmed. The compound [Cu(2)(tu)(6)](SO(4)).H(2)O crystallizes in the P1; space group, with a = 11.079 (2), b = 11.262 (1), c = 12.195 (2) A, alpha = 64.84 (1), beta = 76.12 (1), gamma = 66.06 (1) degrees, and Z = 2. The Cu-thiourea complex is arranged as a Cu(I) tetranuclear ion, [Cu(4)(tu)(12)](4+), sited on a crystallographic inversion center. All copper ions are in a tetrahedral coordination with thiourea ligands and located at alternate sites on an eight-membered, crown-like ring.

Two thiourea-containing gold(I) complexes.

The crystal structures of two salts of bis(thiourea)gold(I) complexes, namely bis(thiourea-kappaS)gold(I) chloride, [Au(CH(4)N(2)S)(2)]Cl, (I), and bis[bis(thiourea-kappaS)gold(I)] sulfate, [Au(CH(4)N(2)S)(2)](2)SO(4), (II), have been determined. The chloride salt, (I), is isomorphous with the corresponding bromide salt, although there are differences in the bonding. The Au(I) ion is located on an inversion centre and coordinated by two symmetry-related thiourea ligands through the lone pairs on their S atoms [Au-S 2.278 (2) A and Au-S-C 105.3 (2) degrees ]. The sulfate salt, (II), crystallizes with four independent [Au(CH(4)N(2)S)(2)]+ cations per asymmetric unit, all with nearly linear S-Au-S bonding. The cations in (II) have similar conformations to that found for (I). The Au-S distances range from 2.276 (3) to 2.287 (3) A and the Au-S-C angles from 173.5 (1) to 177.7 (1) degrees. These data are relevant in interpreting different electrochemical processes where gold-thiourea species are formed.