Thermochemistry of metallic alkyls : Part 7. - The heat of formation of mercury diphenyl, and of mercury phenyl chloride

The heat of reaction of mercury diphenyl with hydrogen chloride in benzene solvent has been measured at 25°C. The heat of reaction of mercury diphenyl with mercuric chloride in methanol solvent has also been measured. From these heats of reaction, the heat of formation of mercury diphenyl has been derived: ΔHf° (Hgφ2, cryst.) = 65.4 ± 2 kcal/mole. Previous data on the heats of reaction of mercury diphenyl with bromine and iodine, and with mercuric bromide and mercuric iodide have been amended, and used to derive, independently, ΔHf° (Hgφ2, cryst.) = 67.2 ± 2.2, and 66.1 ± 3.2 kcal/mole. These values all agree, within their respective limits of error, with the heat of formation obtained by Fairbrother and Skinner from the heat of combustion of mercury diphenyl. The "best" value, ΔHf° (Hgφ2, cryst.) = 66 ± 2.5 kcal/mole, is proposed. The heat of formation of crystalline mercury phenyl chloride is -0.55 ± 2.3 kcal/mole