Crystallographic, vibrational and nuclear magnetic resonance spectroscopic characterization of the [(PhS)2Hg(µ-SPh)2Hg(SPh)2]2– ion

Abstract

The complex [NMe₄]₂[Hg₂(SPh)₆] has been prepared and characterized by X-ray crystallography, vibrational and solid-state NMR spectroscopy. It contains the bitetrahedral [(PhS)₂Hg(µ-SPh)₂Hg(SPh)₂]^2– anion, in contrast to the [NBuⁿ₄]⁺ salt of the same stoichiometry, which contains the distorted-trigonal [Hg(SPh)₃]^– species. The structures of these two species are related in the sense that they both contain relatively strongly bound Hg(SPh)₂ units with weaker bonding to the additional PhS^– ligand(s). This relationship is reflected in the ¹⁹⁹Hg magic angle spinning NMR spectra through similarities in the chemical shift parameters, and in the far-IR and Raman spectra through similarities in the ν(HgS) vibrational frequencies. Solution ¹⁹⁹Hg NMR and electrospray mass spectra of [NMe₄]₂[Hg₂(SPh)₆] indicate that [Hg₂(SPh)₆]^2– dissociates readily into [Hg(SPh)₃]^– in solution, confirming the relative weakness of the bridge bonding in the dinuclear complex.