The reaction of phenyl(dibromochloromethyl)mercury and phenyl(tribromomethyl)mercury with organosilicon and organogermanium hydrides gave bromochloromethyl- and dibromomethyl-substituted derivatives of silicon and germanium via dihalocarbene insertion into the SiH and GeH bonds. The reduction of these products with tri-n-butyltin hydride at room temperature gave the respective monohalomethyl compounds