Phenyl(trichloromethyl)mercury is an organomercury compound with the formula C<sub>6</sub>H<sub>5</sub>HgCCl<sub>3</sub>. It is a white solid that is soluble in organic solvents. The compound is used as a source of dichlorocarbene, e.g. in cyclopropanation reactions, because the products are particularly easy to extract from the reaction mixture. Strong nucleophiles may catalyze the reaction by displacing CCl from mercury, although the free ion is not believed to form in the process. Unusually, the pure organomercury compound reacts with electron-poor alkenes, converting tetrachloroethylene to hexachlorocyclopropane:
The compound is prepared by treating with sources of dichlorocarbene. These include the base/haloform reaction and thermolysis of sodium trichloroacetate:
Closely related compounds include phenyl(bromodichloromethyl)mercury (CAS registry number 3294-58-4) and phenyl(tribromomethyl)mercury (CAS registry number 3294-60-8). According to X-ray crystallography, the former has nearly linear coordination geometry at mercury, with a C-Hg-C angle of 179ð and Hg-C distances of 2.047 à.
Also known is bis(trichloromethyl)mercury, Hg(CCl<sub>3</sub>)<sub>2</sub>.