Correlation of a Solution-State Conformational Change between Mercuric Chloride Complexes of Tris[(2-(6-methylpyridyl))methyl]amine with X-ray Crystallographic Structures.
Solution-state NMR and X-ray crystallography were used to investigate the complexation of HgCl(2) by the potentially tetradentate ligand tris[(6-methyl-2-pyridyl)methyl]amine (TLA) in acetonitrile. A change in the ligand conformation as a function of the metal-to-ligand ratio could be indirectly monitored through large changes in (3)J((1)H(199)Hg) to the methylene protons at -40 degrees C. The solution-state NMR were correlated with two solid-state structures. The five-coordinate complex [Hg(TLA)Cl(2)] (1) crystallizes in the triclinic space group P&onemacr; with a = 8.663(3) Å, b = 11.539(4) Å, c = 13.739(3) Å, alpha = 80.81(2) degrees, beta = 75.84(2) degrees, gamma = 80.97(3) degrees, and Z = 2. The Hg-N(amine) distance of 2.505(7) Å for the tridentate ligand is the same as the average Hg-N(lutidyl) distance of 2.50(3) Å for the two bound lutidyl nitrogens. [Hg(TLA)Cl](2)(Hg(2)Cl(6)) (2) also crystallizes in P&onemacr; with a = 10.606(2) Å, b = 15.104(3) Å, c = 17.785(4) Å, alpha = 67.46(3) degrees, beta = 83.52(3) degrees, gamma = 80.29(3) degrees, and Z = 2. The ligand is tetradentate in the two crystallographically unique cations which are arranged in a dimer-like orientation. The average Hg-Cl distance is 2.37 (1) Å, and the average interionic Hg-Cl distance is 3.51(1) Å. The Hg- N(lutidyl) distances are of two types: two have an average distance of 2.36(3) Å, nearly the same as the Hg-N(amine) distance of 2.35(2) Å. The remaining four N(lutidyl) distances have an average distance of 2.56(5) Å.
Bebout
Deborah C.
DC
Department of Chemistry, Bucknell University, Lewisburg, Pennsylvania.
Bush II
James F.
JF
Crahan
Kathleen K.
KK
Kastner
Margaret E.
ME
Parrish
Damon A.
DA