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

The complex [NMe(4)](2)[Hg-2(SPh)(6)] has been prepared and characterized by X-ray crystallography, vibrational and solid-state NMR spectroscopy. It contains the bitetrahedral [(PhS)(2)Hg(mu-SPh)(2)Hg(SPh)(2)](2-) anion, in contrast to the [NBu(4)(n)](+) 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), units with weaker bonding to the additional PhS ligand(s). This relationship is reflected in the Hg-199 magic angle spinning NMR spectra through similarities in the chemical shift parameters, and in the far-IR and Raman spectra through similarities in the v(HgS) vibrational frequencies. Solution Hg-199 NMR and electrospray mass spectra of [NMe(4)](2)[Hg-2(SPh)(6)] indicate that [Hg-2(SPh)(6)](2-) dissociates readily into [Hg(SPh)(3)](-) in solution, confirming the relative weakness of the bridge bonding in the dinuclear complex.