Thermal decomposition kinetics of polysilanes: Disilane,trisilane, and tetrasilane

The decomposition kinetics of disilane with added butadiene, trisilane both neat and with added butadiene, trimethylsilane or H₂, and normal and iso-tetrasilane both neat and in the presence of added butadiene are reported. Arrhenius parameters of the primary dissociation reactions are determined: A-factors suggest that polysilane decompositions (1) have similar intrinsic activation entropies (ΔS? ≈? 6.2 ± 5 e.u.) and (2) have activation energies which increase with increasing reaction endothermicities. Relative trapping efficiencies of SiH₄, Si₂H₆, Si₃H₈, C₄H₆, Me₃SiH, and H₂ toward SiH₂ and SiH₃SiH are also determined. Other results include the heat of formation of silylsilylene, ΔH ${}_{\text{°}}^{\text{f}}$ (SiH₃SiH) = 75.3 Kcal/mol, and the activation energy for 1,1-H₂ elimination from disilane (EH₂ = 57.8 kcal/mol).