Synthesis, characterization and structures of methylmercury complexes with selenoamino acids

Abstract

Four new methylmercury-selenoamino acid complexes were synthesized, including methylmercury-L-selenoglutathionate, methylmercury-D,L-selenopenicillaminate, and two methylmercury-L-selenomethioninate complexes (one via a Hg–Se bonding and the other Hg–N bonding). All the complexes were characterized by NMR (¹H, ¹³C, ⁷⁷Se and ¹⁹⁹Hg), FT-IR and mass spectra. Their molecular structures were established by single crystal X-ray crystallography (for the Hg–N bonding methylmercury-L-selenomethioninate) and by quantum mechanical calculations using Gaussian-03 with the hybrid functional B3LYP/SDD. All four complexes were found to chemically and structurally resemble their sulfur analogues, with a slightly stronger binding affinity of Hg to Se than to S, suggesting chemical and structural mimicry might play a role in methylmercury-selenium antagonism in biological systems.