Preparation of mercury(II) complexes of tris[(2-pyridyl)methyl]amine and characterization by X-ray crystallography and NMR spectroscopy

The complexation of Hg(II) by the tripodal ligand tris[(2-pyridyl)methyl]amine (TMPA) was investigated by solution state NMR and X-ray crystallography. Mercury coordination compounds exhibiting rarely observed room-temperature solution state NMR (HHg)-H-1-Hg-199 and (CHg)-C-13-Hg-199 satellites were characterized. Solvent, counterion, temperature, and concentration effects on solution state NMR properties were investigated. The solution state NMR were correlated with two solid state structures. The eight-coordinate complex [Hg(TMPA)(2)](ClO4)(2) (1) crystallizes in the monoclinic space group P2(l)/n with a = 9.735(10) Angstrom, b = 10.963(2) Angstrom, c = 18.553(34) Angstrom, beta = 103.81(12)degrees, and Z = 2. The mercury is at the inversion center of a bicapped trigonal antiprism. The Hg-N-amine distance is 2.560(3) Angstrom, and the average Hg-N-pyridyl distance is 2.58(2) Angstrom. The five-coordinate complex [Hg(TMPA)Cl](2)(HgCl4) (2) crystallizes in the triclinic. space group P (1) over bar with a = 11.887(2) Angstrom, b = 13.260(2) Angstrom, c = 15.278(4) Angstrom, alpha = 112.27(2)degrees, beta = 109.39(2)degrees, gamma = 90.670(10)degrees, and Z = 2. The two crystallographically unique cations are distorted trigonal bipyramids. The average Hg-CI distance is 2.355(12) Angstrom, the average Hg-N-amine distance is 2.43(2) Angstrom, and the average Hg-N-pyridyl distance is 2.40(5) Angstrom.