Mercury(II) saccharinate (sac) complexes: Synthesis and molecular structures of [Hg(sac)2(2-ampy)2], [Hg(sac)2(2-ampy)(MeOH)], [Hg(sac)2(2-abt)(MeOH)], [Hg(sac)2(2-abt)(dmso)] (2-ampy = 2-aminopyridine, 2-abt = 2-aminobenzothiazole)

Reaction of [Hg(sac)2] with two equivalents of substituted pyridines, L, [L = 2-aminopyridine (2-ampy), 2-amino-3-methylpyridine (2-ammpy), 4-vinylpyridine (4-vipy), 4-ethylpyridine (4-etpy), 2-acetylaminothiazole (2-aamtz)] in MeOH affords [Hg(sac)2L2], a crystal structure of [Hg(sac)2(2-ampy)2] revealing a distorted tetrahedral HgN4 coordination geometry. When [Hg(sac)2] is refluxed with 2-ampy in MeOH a different product namely, [Hg(sac)2(2-ampy)(MeOH)], is formed selectively a crystal structure showing a distorted tetrahedral HgN3O coordination geometry. Reaction of [Hg(sac)2] with two equivalents of 2-aminobenzothiazole (2-abt) in various solvents did not lead to the disubstituted adduct, but rather solvent-stabilized complexes, [Hg(sac)2(2-abt)(S)] (S = EtOH, MeOH, or dmso) were isolated in high yields, the dmso adduct also being formed upon crystallization of [Hg(sac)2(2-abt)(EtOH)] from dmso. Crystal structures of [Hg(sac)2(2-abt)(MeOH)] and [Hg(sac)2(2-abt)(dmso)] show that the 2-aminobenzothiazole ligand is coordinated though the endocyclic nitrogen atom. Treatment of [Hg(sac)2] with two equivalents of 2-acetylaminothiazole (2-aamtz) yields [Hg(sac)2(aamtz)2] which, on the basis of spectroscopic data, is proposed to contain an octahedral mercury(II) center with both 2-aamtz ligands coordinating in a bidentate manner through the endocyclic N-atom of the thiazole ring and the oxygen atom of the acetyl group.

[Hg(sac)2] is a useful precursor towards a range of four-coordinate Hg(II) bis(saccharinate) complexes. Addition of two equivalents of substituted pyridines (L) affords tetrahedral HgN4 complexes, [Hg(sac)2L2], while with 2-aminopyridine in MeOH the HgN3O species [Hg(sac)2(2-ampy)(MeOH)] is selectively formed. Reactions with 2-aminobenzothiazole (2-abt) in various solvents selectively yield related HgN3O solvent-stabilized complexes, [Hg(sac)2(2-abt)(S)]. Crystal structures of four of these complexes are presented with all adopting a distorted tetrahedral coordination geometry at mercury.Figure optionsDownload as PowerPoint slide