Yuki Matsunaga

Group 12 metal(II) complexes with 1-methylimidazoline-2(3H)-thione (mitH): correlation between crystal structure and physicochemical property

The crystal structures of [ZnX2(mitH)2] (X = Cl (1), Br (2)), [ZnI(mitH)3]I (3), and [CdX2 (mitH)2] (X = Cl (4), Br (5), I (6)) (mitH = 1-methylimizadoline-2(3H)-thione) were determined by X-ray crystallography and all complexes were characterized by IR, far-IR, Raman, and UV–Vis absorption (solid) spectroscopies. All complexes except 3, which have a different ZnIS3 coordination mode, have a distorted tetrahedral geometry with an MX2S2 coordination mode. Each π-character of the C=S bonds (from 37.7 to 45.4%) is smaller than that of free mitH (51.9%). Their M–S–C bond angles (from 97° to 109°) support that the C=S bonds are not a full double bond. Their stretching vibration frequencies of M–S (300–320 cm−1) and M–X (229–290 cm−1) in both far-IR and Raman spectra show the lower energy shifts with increasing weight of metal(II) or halide ions. Similarly, some shifts (from 275 nm for 1 to 293 nm for 6) are also observed in CT transition bands in UV-Vis absorption spectra.