Aryl-mercury bond dissociation

The Arrhenius parameters and the thermochemical sum of the phenyl-carbon and phenyl-halogen bond dissociation energies are shown in Table 8. The extent of the diphenyl mercury decomposition was determined from the weight of mercury produced. It is the present author s opinion that in calculating the Arrhenius parameters for this compound Carter et al.81 gave too great a statistical 

No kinetic data are available but numerous references to related pyrolysis and photolysis studies are given. The product distribution from the decomposition of dibenzyl mercury under a variety of conditions has also been reported (ref. 110 lists the pertinent papers). 

The primary step in the photolysis of phenyl mercuric cyanide and cyclohexyl mercuric cyanide in methanol at room temperature is mercury-phenyl or mercury-cyclohexyl bond rupture111. The subsequent steps in the mechanism are complex, but do not involve the parent substance. Reactions involving HgCN must be postulated to explain the observed product, so that this radical must have a finite existence. 

The thermal decomposition and photolysis of this alkyl have been studied by Buchanan and Creutzberg112. The pyrolysis mechanism is not fully understood. The overall process is first-order and is unaffected by an 8.5-fold increase in surface-to-volume ratio. Based on measurements of pressure increase, the reaction exhibits an induction period ranging from 2-3 minutes at 513 °C to 40 minutes at 466 °C. Short chains are apparently involved. A polymer initially of empirical formula (BCH2) but slowly losing hydrogen to form (BCH) is deposited on the surface. The mechanism probably involves the reactions 

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