INTERACTION OF ZN2+, CD2+, AND HG2+ WITH 2-(ALPHA-HYDROXYBENZYL)THIAMIN AND 2-(ALPHA-HYDROXY-ALPHA-CYCLOHEXYLMETHYL)THIAMIN - CRYSTAL-STRUCTURE OF THE COMPLEX HG(2-(ALPHA-HYDROXYBENZYL)THIAMIN)CL3.H2O

The reactions of ZnCl2, CdCl2, and HgCl2 with the “active aldehyde derivatives” of thiamin, 2-(α-hydroxybenzyl)thiamin (HBT) and 2-(α-hydroxycyclohexylmethyl)thiamin (HCMT) were studied in methanolic and aqueous solutions. Complexes of the formulas M(HBT)C13 and M(HCMT)C13, (M = Zn2+, Cd2+, Hg2+) were isolated and characterized as solid adducts with elemental analyses, conductivity measurements, and 1R spectra. The crystal structure of the complex Hg(HBT)Cl3 was also solved. The compound is monoclinic (P21/n) with a = 9.588 (6) Å, b = 7.644 (3) Å, c = 31.412 (20) Å, β = 90.41 (5)°, V = 2302 (2) Å3, and Z = 4. The HBT ligand is found in the S conformation, as expected for C(2)-substituted derivatives of thiamin, with = 172.7° and ΦT =-100.0°. It is concluded from the IR spectra that all the isolated complexes are isostructural and in the same 5 conformation, as in the compound Hg(HBT)Cl3, in the solid state. The facile formation of complexes of bivalent metals with the active aldehyde derivatives of thiamin, which contain direct metal-ligand (M-N(l')) bonding, may indicate that the intervention of metal ions could follow the formation of these intermediates in the enzymatic action of thiamine. © 1990, American Chemical Society. All rights reserved.