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 solutionstate NMR 1 H 199 Hg 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 ](ClO 4 ) 2 ‚0.5toluene (1) crystallizes in the triclinic space group P1 h with a ) 10.953(5) Å, b ) 12.812(5) Å, c ) 13.006(5) Å, R ) 67.50(3)°, β ) 82.74(3)°, γ ) 67.88(3)°, and Z ) 2. The Hg-N amine bonds are 2.404(4) and 2.350(4) Å and the Hg-N pyridyl bond lengths are similar, ranging from 2.352(4) to 2.557(5) Å. 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 square planar complex [Hg(BMPA)NCCH 3 ](ClO 4 ) 2 ( 7) crystallizes in the monoclinic space group P2 1 /c with a ) 12.987(2) Å, b ) 17.469(4) Å, c ) 8.886(2) Å, β ) 95.200(12)°, and Z ) 4. The Hg-N amine distance is 2.403 Å, the average Hg-N pyridyl distance is 2.23 Å, and the Hg-N nitrile distance is 2.229 Å. The BMPA ligand is bound to Hg(II) in a meridional fashion with a solvent molecule in the same plane and close associations to two axial perchlorates with Hg-O distances of 2.707(7) and 2.90(2) Å. Solution NMR studies support limited dynamics for a cation with similar interactions between BMPA and Hg(II).

Synthesis, Stability Constant Determination, and Structural Study of Some Complexes of a Zinc Triad Containing Pyridyl‐amine‐quinoline and Pyridyl‐thio‐quinoline

“…This phenomenon had already been observed, [13] and was traced back to the interactions occurring between the ring currents of the opposite rings of the bis coordinated ligand. A down-field shift of the aromatic protons would be otherwise observed upon ligand coordina-tion.…”

“…A search in the CCD returned only five structures, in which the Hg-O distance ranges between 2.569 and 2.932 Å. The only six-coordinate Hg complex reported [13] shows Hg-O distances of 2.569 and 2.650 Å, comparing well with our value of 2.60(1) Å. Like in 1 above, the oxygen atoms of the two perchlorate residues and the quinolyl N atom of the bidentate NSN(Qui) donor are involved in a network of nonbonding interactions.…”

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

“…[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.…”

Crystal Structure of a Polymeric Hg(II) Complex of a Pyridine Containing a Self-Assembling System

“…The Hg-N bond distance is 2.184 (6) 5 The Hg-N bond length ranges in these complexes from 2.193 to 2.557 Å (mean 2.375 Å). The Hg-Cl bond distance in the complex is 2.307(2)Å, which is close to the same distance in HgCl2 (2.25 Å).…”