Solid-state and solution-state coordination chemistry of the zinc triad with the mixed N,S donor ligand bis(2-methylpyridyl) sulfide

The binding of group 12 metal ions to bis(2-methylpyridyl) sulfide (1) was investigated by X-ray crystallography and NMR. Seven structures of the chloride and perchlorate salts of Hg(II), Cd(II), and Zn(II) with 1 are reported. Hg(1)(2)(ClO4)(2), Cd(1)(2)(CIO4)(2), and Zn(1)(2)(ClO4)(2)(CH3CN)-C-. form mononuclear, six-coordinate species in the solid state with 1 binding in a tridentate coordination mode. Hg(1)(2)(ClO4)(2) has a distorted trigonal prismatic coordination geometry while Cd(1)(2)(ClO4)(2) and Zn(1)(2)(CLO4(4))(2)-CH3CN have distorted octahedral geometries. With chloride anions, the 1:1 metal to ligand complexes Hg(l)Cl-2, [Cd(1)Cl-2](2), and Zn(1)Cl-2 are formed. A bidentate binding mode that lacks thioether coordination is observed for 1 in the four-coordinate, distorted tetrahedral complexes Zn(1)Cl-2 and Hg(1)Cl-2. [Cd(1)Cl-2](2) is dimeric with a distorted octahedral coordination geometry and a tridentate 1. Hg(l)Cl-2 is comprised of pairs of loosely associated monomers and Zn(l)Cl-2 is monomeric. In addition, Hg-2(1)Cl-4 is formed with alternating chloride and thioether bridges. The distorted square pyramidal Hg(II) centers result in a supramolecular zigzagging chain in the solid state. The solution H-1 NMR spectra of [Hg(1)(2)](2+) and [Hg(1)(NCCH3)(x)](2+) reveal (3-5)J((HgH)-Hg-199-H-1) due to slow ligand exchange found in these thioether complexes. Implications for use of Hg(II) as a metallobioprobe are discussed.