Predominant ionic interactions in CdS4N2 and HgS4 coordination environments

Synthesis and spectral investigation of [Cd(cpzdtc)2] (1), [Cd(cpzdtc)2(1,10-phen)] (2), [Cd(cpzdtc)2(2,2′-bipy)]0.4H2O (3), [Hg(cpzdtc)2] (4), [Hg(cpzdtc)2(1,10-phen)] (5), [Hg(cpzdtc)2(2,2′-bipy)] (6) (where cpzdtc = cinnamylpiperazinedithiocarbamate, 1,10-phen = 1,10-phenanthroline and 2,2′-bipy = 2,2′-bipyridine) and single-crystal X-ray structures of 3 and 4 are reported. 1H NMR spectra show deshielding of the protons attached to C4 and C4′ and 13C NMR signal of the thioureide carbons are observed at 203.4, 206.6, 206.5, 203.3, 206.7 and 206.6 ppm for 1–6. X-ray photoelectron spectroscopy (XPS) chemical shifts clearly indicate localization of positive charge on the central metal ions and for adducts involving mercury, very little change is observed in the binding energies of Hg4f7/2, N1s and S2s electrons, indicating predominant ionic interaction. Single-crystal X-ray structural analysis of 3 showed cadmium is in a distorted octahedral environment with CdS4N2 chromophore, whereas in 4, mercury is in a distorted tertrahedral coordination environment. BVS values were 1.993 for 3 and 2.166 for 4, supporting predominantly ionic interaction consistent with XPS data.