Tridentate ligand N-(2-pyridylmethyl)-N-(2-(ethylthiolato)amine (L) forms the novel complex [Hg(5)(L)(6)](ClO(4))(4).toluene () with a bicyclo[3.3.3] Hg(5)S(6) core and 4-, 5- and 6-coordinate metal centers; characterization of a solution of by ESI-MS revealed elaborate speciation involving [Hg(n)L(n+1)(ClO(4))(n-2)](+), [Hg(n)L(n)(ClO(4))(n-1)](+) and [Hg(n)L(n-1)(ClO(4))(n)](+) ion families.

Divalent zinc triad metal ion complexes of type M(L)(2)(ClO(4))(2) (L = N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine) with N(4)S(2) metal coordination spheres were isolated and characterized by X-ray crystallography and variable temperature proton NMR. Although bis-tridentate chelates have nine geometric isomers, the crystallographically characterized complexes of all three metal ions had trans facial octahedral coordination geometry with C(i) symmetry. Despite the low coordination number and geometric preferences of d(10) metal ions, which facilitate inter- and intramolecular exchange processes, dilute solutions of these bis-tridentate chelates exhibited slow geometric isomerization. Symmetry, sterics and shielding arguments supported specific isomeric assignments for the major and minor chemical shift environments observed at low temperature. At elevated temperature, rapid intramolecular exchange occurred for all three complexes but slow intermolecular exchange on the coupling constant time scale was evidenced through detection of J(HgH) interactions for Hg(L)(2) (2+). These unusual observations are discussed in the context of the zinc triad metal ion coordination chemistry of related bis-tridentate chelates.

2007) Zinc triad metal ion complexes of NN′S ligand N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine, Main Group Chemistry, 6:3-4, 155-168,The coordination chemistry of divalent zinc triad metal ions with N-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine (L) was investigated by X-ray crystallography and proton NMR. Chloride salts yielded non-homologous M(L)Cl 2 complexes. Hg(L)Cl 2 and Zn(L)Cl 2 were fivecoordinate monomers with distorted square pyramidal and trigonal bipyramidal geometries, respectively. Cd(L)Cl 2 formed a six-coordinate polymer with a distorted octahedral geometry. These complexes had similar nearly temperature independent proton NMR spectra suggesting structural differences between them were less extensive in solution due to fluxional processes. Although 1:1 metal to ligand complexes were most thermodynamically stable for the chloride salts at all [M 2þ ]/[L], the thermodynamic stability of [M(L)(NCCH 3 ) x ] 2þ only exceeded that of [M(L) 2 ] 2þ when [M 2þ ] ! [L] with perchlorate salts. Slow intramolecular and intermolecular exchange conditions for [M(L) 2 ] 2þ and slow intermolecular exchange conditions for [M(L)(NCCH 3 ) x ] 2þ were found on the proton chemical shift and in some cases J(M 1 H) time scales. Strong interactions between divalent zinc triad metal ions and thioether ligand components at physiologically relevant temperatures suggest interactions with methionine should be considered in developing a more complete understanding of the bioactivities of these metal ions.