COPPER-63 NUCLEAR-QUADRUPOLE RESONANCE FREQUENCIES AND MOLECULAR GEOMETRIES OF 3-CO-ORDINATE COMPLEXES OF COPPER(I) HALIDES WITH N-ALKYLIMIDAZOLIDINETHIONE AND THIAZOLIDINETHIONE LIGANDS

The crystal structures of seven three-co-ordinated complexes of copper (I) halides with thione ligands, [CuXL2], where L = 1,3-thiazolidine-2 -thione and X = Cl or Br, L = N-ethylimidazolidine-2-thione and X = Br , L = N-isopropylimidazolidine-2-thione and X = Cl or Br, and L = N-pr opylimidazolidine-2-thione and X = Cl or I have been determined. In al l complexes, the copper lies in a trigonal-planar environment and the thiazolidine or imidazolidine rings show no major distortion from plan arity. Owing to the presence of hydrogen bonding involving H[N(2)], or H[N(02)], and the halogen atom all complexes adopt a W-shaped conform ation. The Cu-63 NQR frequencies of these complexes, together with tho se of two other similar complexes whose structures were already availa ble, depend, for a given halide, on the S-Cu-S bond angle, a decrease in angle producing an increase in resonance frequency: V(Cl) = 28.7 - 0.544DELTAGTHETA and V(Br) = 26.9 - 0.229DELTATHETA MHz, where DELTATH ETA is the difference between the S-Cu-S bond angle and 120-degrees-C. This behaviour has been rationalized in terms of a partial field-grad ient model of the resonance frequencies.