Characterization of Mercury(II) Complexes of Bis[(2-pyridyl)methyl]amine by X-ray Crystallography and NMR Spectroscopy

Abstract

Solution-state NMR and X-ray crystallography were used to investigate the complexation of Hg(II) by the tridentate ligand bis[(2-pyridyl)methyl]amine (BMPA). Mercury coordination compounds exhibiting rarely observed solution-state NMR 1H199Hg satellites were characterized. Temperature and concentration effects on solution-state NMR properties were investigated. The solution-state NMR were correlated with two solid-state structures. The distorted trigonal prismatic complex [Hg(BMPA)2](ClO4)2·0.5toluene (1) crystallizes in the triclinic space group P1 with a = 10.953(5) A, b = 12.812(5) A, c = 13.006(5) A, α = 67.50(3)°, β = 82.74(3)°, γ = 67.88(3)°, and Z = 2. The Hg−Namine bonds are 2.404(4) and 2.350(4) A and the Hg−Npyridyl bond lengths are similar, ranging from 2.352(4) to 2.557(5) A. Solution NMR studies are consistent with rapid equilibrium between isomeric trigonal prismatic and facial octahedral forms of this complex. A twisting mechanism is proposed to mediate interconversion. The distorted squar...