Silacyclopropanes, decomposition

Thermolysis of l,l-diadamantyl-2,3-dialkylsilacyclopropanes generated diadamantylsilylene, which was then trapped with cis- and /ra/M-2-butene and -3-hexene. The complete stereospecificity of silacyclopropane decomposition and silylene-alkene addition suggests an intermediate silylene in a singlet ground state (Equations (43) and (44)) <91JA1281). 

Silacyclopropane, 1,1 -difluorotetramethyl-decomposition, 1, 587 Silacyclopropanes, I, 575-581 ring expansion, I, 587 Silacyclopropenes, I, 583-587 minimum energy geometry, I, 587 ring expansion, 1, 587 7-Siladispiro[2.0.2.1 jheptane synthesis, I, 576... 

The thermodynamic stability of unsubstituted silacyclopropane to fragmentation has been studied by ab initio quantum mechanical methods and the enthalpy of decomposition to H2Si + CH2=CH2 was predicted to be 44.878 and 43.279 kcalmol-1. There is indirect experimental support for these theoretical estimates. When these values were employed in RRKM calculations on silirane decomposition, the pressure dependence of the bimolecular rate constant for addition of H2Si to ethylene could be accurately modeled80. 

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