VIBRATIONAL-SPECTRA AND CRYSTAL-STRUCTURES OF TRISKIS(ETHYLENETHIOUREA)COPPER(I) AND TETRAKIS(ETHYLENETHIOUREA)COPPER(I) SYSTEMS

A room-temperature redetermination of the crystal structure of [Cu(SC(NHCH2)(2))(3)](2) (SO4) has been carried out. The original determination, recorded in communication format in space group Ic, Z = 4, seemingly with the full formula as the asymmetric unit, is at variance with our findings which describe the structure in space group R3c, a 12.741(7), c 35.59(1) Pi (hexagonal setting), Z = 6, with one-third of each of two independent cations, each lying on a threefold axis, comprising the asymmetric unit. The sulfate ion also lies on a threefold axis in proximity to only one of the two cations, the S-O axial bond approaching the copper atom normal to the planar CuS3 array [Cu-S, O 2.269(2), 2.834(8) Angstrom]; in the other cation, unperturbed by any sulfate approach, Cu-S is appreciably shorter [2246(2) Angstrom]. R was 0.029 for 905 'observed' reflections. A redetermination of the structure of tetrakis (ethylenethiourea) copper(I) nitrate is also recorded; crystals are triclinic, $($) over bar$$ P1, a 13.211(2), b 11.2167(4), c 7.566(3) Angstrom, alpha 81.93(2), beta 78.35(3), gamma 87.22(1)degrees, Z = 2, R being 0.031 for 3861 independent 'observed' reflections. The copper environment is quasi-tetrahedral, Cu-S ranging between 2.3322(9) and 2.3658(12) Angstrom, and S-Cu-S 98.76(3)-117.83(3)degrees. The vibrational (far-infrared and Raman) spectra are recorded for these CuSn systems, and discussed and assigned in the light of the structural results.