Phenylmercury Chloride: Its Single-Crystal X-Ray Structure and Some Aspects of its Biological Chemistry

Abstract

A single crystal of phenylmercury chloride (PhHgCl) was obtained by serendipity from a solution of diphenylmercury (HgPh2) and dihydrolipoic acid in tetrahydrofuran / carbon tetrachloride. The crystal structure of PhHgCl is pseudotetragonal. It is best described in the orthorhombic space group Cmma with a = 6.856(1), b = 6.882(1), c = 14.309(2) Å (at 193 K), and Z = 4. The Cl-Hg-C moiety of the PhHgCl molecule is exactly linear. The bond lengths at the Hg atom are Hg-Cl 2.345(2) and Hg-C 2.044(9) Å. In the crystal, the molecules are arranged in double layers parallel to the a,b plane. In a model medium for the gastric juice (0.1 M DCl in D2O / [D8]dioxan, 37 °C), HgPh2 reacts to form PhHgCl. HgCl2, which would result from complete dearylation, cannot be isolated from the reaction mixture. However, it appears that a small equilibrium concentration of HgCl2 may be present, because on addition of 1,4,7-trithiacyclononane (ttcn) and diethyl ether, the dichloride can be trapped as solid [Hg(ttcn)2][HgCl4]. We estimate that after oral uptake of HgPh2 20 -90% are transformed into PhHgCl in the stomach after 30 min