Mercurophilic interaction in novel polynuclear Hg(ii)–2-aminoethanethiolates

Abstract

The reaction of 2-aminoethanethiol hydrochloride with Hg₂Cl₂ in water yielded elemental mercury and one-dimensional polynuclear compounds [{Hg₃Cl₅(SCH₂CH₂NH₃)₃}Cl]_n (1) and [HgCl(SCH₂CH₂NH₂)(H₂O)₂]_n (2). The coordination environment around Hg in 1 and 2 is quite variable despite similar reaction conditions. The formation of a five-membered S/N chelate in 2 can be attributed to the use of base to produce a neutral ligand. Three independent types of Hg atoms, both three- and four-coordinate are observed in 1, whereas in 2, the Hg atom is tetracoordinate with S, N and Cl atoms in the primary coordination sphere. Despite distinct structural chemistry, the coordination environments in 1 and 2 are fairly similar with repeating units connected with bridged thiolate S atoms in addition to a terminal Cl attached to Hg. Intermolecular hydrogen-bonding involving amine protons, Cl and water molecules are responsible for a three-dimensional network in both 1 and 2. A short Hg⋯Hg distance of 3.564 Å, indicates the presence of a mercurophilic interaction in 1. The compounds have been characterized by ¹H and ¹³C NMR, UV-Vis, FT-IR, Raman, mass spectrometry, TGA and single X-ray crystallography.