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

Abstract

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 1H199Hg and 13C199Hg 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 P21/n with a = 9.735(10) Å, b = 10.963(2) Å, c = 18.553(34) Å, β = 103.81(12)°, and Z = 2. The mercury is at the inversion center of a bicapped trigonal antiprism. The Hg−Namine distance is 2.560(3) Å, and the average Hg−Npyridyl distance is 2.58(2) Å. The five-coordinate complex [Hg(TMPA)Cl]2(HgCl4) (2) crystallizes in the triclinic space group P1̄ with a = 11.887(2) Å, b = 13.260(2) Å, c = 15.278(4) Å, α = 112.27(2)°, β = 109.39(2)°, γ = 90.670(10)°, and Z = 2. The two crystallographically unique cations are distorted trigonal bipyramids. The average Hg−Cl distance is 2.355(12) Å, the average Hg−Namine distance is 2.43(2) Å, and the average Hg−Npyridyl distance is 2.40(5) Å.

Structural, Spectroscopic, and Reactivity Properties of N2S2(thioether)‐O(amide)‐Ligated HgII Complexes: The First Examples of HgII‐Mediated Amide Cleavage

“…Comprehensive solution infrared and NMR studies of these complexes has revealed that strong N 2 S 2 and amide oxygen coordination are maintained in CH 3 -2 mmol). The resulting mixture was stirred for ca.…”

“…[14] Typically, Hg II -S(thioether) bond lengths are found in the range of 2.47-2.73 Å. [10][11][15][16] Thus, the Hg(1)-S(2) interaction is consistent with strong coordination to the Hg II center, whereas the Hg (1) [3] Perchlorate coordination to Hg II has been observed in several previously reported complexes. [4,[17][18][19][20][21] In these, the Hg II -O(perchlorate) bond lengths generally range from 2.66-2.95 Å.…”

“…[1][2]1 H NMR studies of Hg II complexes of tripodal ligands have contributed to our understanding of the interplay of Hg II coordination and spectroscopic properties by providing information regarding the magnitude of J199 Hg 1 H and J199 Hg 13 C coupling constants as a function of the nature of the Hg II ligand environment. [3][4][5][6][7] Herein we outline the synthesis, structural and spectroscopic characterization, and amide cleavage properties of two Hg II 3 interactions. Second, we have commenced investigations into biologically-relevant reactions as a function of the group 12 metal ion present.…”

“…[28] [(bmppa)Hg(ClO 4 4 -NOH·5H 2 O (3.4 mg, 0.019 mmol) and an internal standard (CHPh 3 , 4.5 mg, 0.019 mmol). The resulting mixture was monitored by 1 H NMR at 55(1)°C at two-minute intervals for 50 minutes at which point the reaction had reached completion, as indicated by the formation of one equivalent of (CH 3 ) 3 C(O)OCD 3 . The…”

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

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