Correlation of a Solution-State Conformational Change between Mercuric Chloride Complexes of Tris[(2-(6-methylpyridyl))methyl]amine with X-ray Crystallographic Structures

Abstract

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.

Zinc triad metal ion complexes ofNN′S ligandN-(2-pyridylmethyl)-N-(2-(methylthio)ethyl)amine

“…(7) Å are comparable with those found in Hg(L 3 )Cl 2 [8]. HgÀ ÀN alkyl distances of 2.268(7) and 2.291(7) Å are shorter than the range previously reported for five-coordinate Hg(II) complexes [8,17,18], likely due at least in part to the modest donor abilities of the thioether donor. The Hg-S bond lengths [2.911(2) Å (Hg(1), 2.881(2) Å (Hg (2)], similar to complex 1, are longer than other comparable Hg-thioether distances [8].…”

“…Interestingly, significant broadening at cryogenic temperatures suggests the rate of an intramolecular isomerization process was approaching the chemical shift time scale. However, intramolecular isomerization does not preclude detection of J(M 1 H) [6,7,17]. Proton NMR spectra in alternative solvents were comparable, suggesting negligible solvent involvement in solution equilibria.…”

Hybrid (Te, N) and (N, Te, N) ligands having pyrrolidine ring and their palladium(II) and mercury(II) complexes: synthesis and crystal structures

“…The Hg Ã/Te bond length of 2.747(1) Å is consistent with the earlier report of 2.728(1) Å for [HgBr(1-(NMe 2 )-2-(TeC 6 H 4 -4-OEt)-4-MeC 6 H 5 )] 2 [15]. The Hg Ã/N bond length of 2.457(4) Å is within the range of values reported in literature [16,17] for complexes of Hg with various nitrogen donors [2.226(9) Á/2.505(7) Å ]. In this case it is longer than the sum of the covalent radii of mercury and nitrogen (ca 2.23 Å ) suggesting relatively weak coordination which is consistent with the conclusions reached from the NMR spectra.…”

Hg(II) coordination complexes containing the tris(2-pyridylmethyl)amine ligand: Synthesis, characterization and crystal structure analysis

“…X-ray diffraction data for 2 was collected at 130(1) K by the ω-scan technique on an Agilent Technologies four-circle diffractometer equipped with an Eos CCD-detector using graphitemonochromatized Mo-Kα radiation (λ = 0.71073 Å) [18]. The calculations were mainly performed within the WinGX program system [19].…”

“…However, there are fewer reports concerning complexation of the Hg(II) ion by tripodal ligands containing exclusively nitrogen donor atoms [17,18].…”