Synthesis of two complexes of cadmium(II) iodide with benzenecarbothioamide (BCTA): Crystal and molecular structure of [Cd(BCTA)2I2]

The reaction between CdI₂ and benzenecarbothioamide (BCTA) in ethanol produces crystalline [Cd(BCTA)₂I₂] but in 1,2-dichloroethane it yields [Cd(BCTA)I₂] in powder form. [Cd(BCTA)₂I₂] has been characterized by X-ray crystallography, and both complexes have also been identified by infrared spectra in the solid phase, ¹H NMR, and electrical conductivity studies in solution. The crystals of [Cd(BCTA)₂I₂] are monoclinic, space group P2₁/c, with a = 747.6(1) pm, b = 1958.7(13) pm, c = 1363.6(6) pm, β = 110.307(3)° and Z = 4. Least-squares refinement of the structure based on 4260 observations led to final discrepancy indices of R = 0.043 and R_w = 0.054. The geometry around the cadmium atom is slightly distorted from the tetrahedral. The BCTA is coordinated through the sulphur atom: CdI(1) = 277.2(1) pm, CdI(2) = 272.6(1) pm, CdS(1) = 256.7(3) pm, CdS(2) = 257.5(2) pm. The electrical conductivity studies and NMR and IR spectra are consistent with the structure found for [Cd(BCTA)₂I₂] and suggest a dimeric trans symmetric tetrahedral structure with halogen bridging (C_2h) for [Cd(BCTA)I₂].