Synthesis and molecular structures of methyl and phenylmercury(II) complexes with benzaldehyde-4,4-dimethylthiosemicarbazone

Abstract The reactions of benzaldehyde-4,4-dimethylthiosemicarbazone ( LH ) with methyl and phenylmercury (II) chlorides in different conditions were investigated. From the methyl derivative, two complexes [HgMeClLH] ( 1 ) and [HgMeL] ( 2 ), were obtained working in ethanol in the absence or the presence of basic medium respectively. However, in the same conditions only the complex [HgPhL] ( 3 ) was isolated. The corresponding complex containing the neutral ligand [HgPhClLH] ( 4 ) was prepared in refluxing dicloromethane. Furthermore, in the presence of hydrochloric acid, HgPhCl undergoes a symmetrization reaction to afford HgPh 2 and [Hg(LH) 2 (μ-Cl) 2 HgCl 2 ], reported previously from the reaction with HgCl 2 . Spectroscopic studies and X-ray structural analysis showed that the thiosemicarbazone is always SN coordinated, giving a distorted tetrahedral arrangement in complexes 1 and 4 and a distorted T-shaped stereochemistry around the mercury centre in complexes 2 and 3 .