The silicon–silicon bond dissociation energy in hexamethyldisilane

Abstract

Hexamethyldisilane has been pyrolysed in a static system between 523 and 555° at initial pressures of 0·2 to 0·8 mm.Hg. The product composition was determined, and the rate of formation of products found to be of the first order,k(sec.^–1)= 10^{13·5 ± 1·0} exp –(67,300 ± 2,200)/RT. The activation energy is identified with the bond dissociation energy, D(Me₃Si–SiMe₃), and a mechanism suggested which accounts for the products and kinetic features, and, qualitatively, for the different results of other workers. The ionisation potential of the trimethylsilyl radical is calculated to be 7·1 eV.