COPPER-63,65 NUCLEAR-QUADRUPOLE RESONANCE STUDIES OF COPPER(I) COMPLEXES WITH SULFUR-CONTAINING LIGANDS .2. BIS (1-ALKYLIMIDAZOLIDINE-2-THIONE)COPPER(I) IODIDES AND RELATED-COMPOUNDS

The Cu-63 NQR resonances frequencies of ten three-co-ordinated copper( I) complexes, in each of which at least two of the ligands are thiones , have been determined. The Zeeman splitting of the Cu-63 NQR spectrum of a single crystal of bis(tetrahydro-1 H-pyrimidine-2-thione)copper( I) chloride yields the value of 0.36(2) for the asymmetry parameter wi th the field-gradient z axis perpendicular to the CuS2Cl plane and the y axis along the Cu-Cl bond. The crystal structure of a representativ e member of these complexes, bis(1-propyl-imidazolidine-2-thione)coppe r(I) iodide, confirms the three-co-ordination of the Cu(I). When one o f the ligands is a halogen atom the results confirm the previously rep orted trend that, for a given ligand, the Cu-63 NQR resonance frequenc ies of the complexes [CuL2X] are in the order Cl > Br > 1. For two of the complexes the temperature dependence of the NQR frequency indicate s that a phase change occurs in the range 77-300 K.