Cleavage of Hg–C Bonds of Organomercurials Induced by Im<sup>OH</sup>Se via Two Distinct Pathways

Published on 2017-10-12T19:33:36Z (GMT) by
We show that the <i>N</i>-methylimidazole-based selone Im<sup>OH</sup>Se having an N–CH<sub>2</sub>CH<sub>2</sub>OH substituent has the remarkable ability to degrade methylmercury by two distinct pathways. Under basic conditions, Im<sup>OH</sup>Se converts MeHgCl into biologically inert HgSe nanoparticles and Me<sub>2</sub>Hg via the formation of an unstable intermediate (MeHg)<sub>2</sub>Se (pathway I). However, under neutral conditions, in the absence of any base, Im<sup>OH</sup>Se facilitates the cleavage of the Hg–C bond of MeHgCl at room temperature (23 °C), leading to the formation of a stable cleaved product, the tetracoordinated mononuclear mercury compound (Im<sup>OH</sup>Se)<sub>2</sub>HgCl<sub>2</sub> and Me<sub>2</sub>Hg (pathway II). The initial rate of Hg–C bond cleavage of MeHgCl induced by Im<sup>OH</sup>Se is almost 2-fold higher than the initial rate observed by Im<sup>Me</sup>Se. Moreover, we show that Im<sup>Y</sup>Se (Y = OH, Me) has an excellent ability to dealkylate Me<sub>2</sub>Hg at room temperature. Under acidic conditions, in the presence of excess Im<sup>Y</sup>Se, the volatile and toxic Me<sub>2</sub>Hg further decomposes to the tetracoordinated mononuclear mercury compound [(Im<sup>Y</sup>Se)<sub>4</sub>Hg]<sup>2+</sup>. In addition, the treatment of Im<sup>OH</sup>Se with MeHgCys or MeHgSG in phosphate buffer (pH 8.5) afforded water-soluble Hg­(SeS) nanoparticles via unusual ligand exchange reactions, whereas its derivative Im<sup>OMe</sup>Se or Im<sup>Me</sup>Se, lacking the N–CH<sub>2</sub>CH<sub>2</sub>OH substituent, failed to produce Hg­(SeS) nanoparticles under identical reaction conditions.

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Banerjee, Mainak; Roy, Gouriprasanna (2017): Cleavage of Hg–C Bonds of Organomercurials

Induced by ImOHSe via Two Distinct Pathways. ACS Publications. Collection.