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Theoretical kinetic and thermodynamic study on the disilene‐silylsilylene isomerization
Author(s) -
GuanZhi Ju,
WanYong Ma,
CongHao Deng,
Christoffel Kurt
Publication year - 1988
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560340839
Subject(s) - isomerization , chemistry , reaction rate constant , exothermic reaction , kinetic energy , thermodynamics , transition state theory , enthalpy , atmospheric temperature range , kinetics , computational chemistry , physics , organic chemistry , quantum mechanics , catalysis
The titled isomerization has been studied at the HF/3–21G level. The changes in thermodynamic functions, equilibrium constant K(T), conversion efficiency C(T), and the rate constant k (T) for the isomerization have been calculated using our energies of the reactant (R), transition state (TS), and product (P), their harmonic vibrational frequencies, and the classical and corrected barrier (by vibrational zero‐point energies). In the range of temperature, 300–1200K, ΔH < 0, ΔS > 0 and ΔG < 0; i.e., it is exothermic, increasing in the entropy, and spontaneous reaction. ΔS ≠ < 0, log A is about 12.0 ±0.15 ( s −1 ), but the k (T) is from 2.627 × 10(−33) to 6.933 × 10(8) (5 −1 ); i.e., it passes through a tight TS, the A factor changes little, but the rate constant varies rapidly with the temperature. These results agree with the fact that the isomerization occurs readily at high temperature. Furthermore, Newman's mechanism, 2SiH 2 → (H 2 SiSiH 2 )* → (HSiSiH 3 )* → Si 2 H 2 + H 2 , is supported. Similarly, the isomerization, HDSiSiH 2 → HSiSiDH 2 , is also studied.