Solution behavior of Hg(II)-cystamine by Uv-Vis and199Hg NMR

Abstract

The combination of HgCl2 with the disulfide salt of 2-aminoethanethiol (cystamine dihydrogen dichloride) in water yields a two-dimensional chain {[HgCl4][(NH3CH2CH2S[sbnd])2]}n (1). It consists of six-coordinate Hg in [HgCl4]n units with bridging and termainal Cl atoms. The disulfide groups, (NH3CH2CH2S[sbnd])2 are held between the [HgCl4]n chain with weak S[sbnd]S interactions. The chlorides in the [HgCl4]n units are involved in intermolecular hydrogen bonding to yield a three-dimensional network. A similar reaction with the reduced form of cystamine (2-amino ethanethiol) yields a linear Hg(II)-bis-thiolate, [Hg(SCH2CH2NH3]2+ (2). When compound 1 is combined with two equivalents of NaOH it rearranges to 2 as indicated by 199Hg NMR and Uv-Vis.