Theoretical studies on the structures and isomerization of silylenoid H2SiNaCl

The structures and isomerization of silylenoid H2SiNaCl were studied by ab initio molecular orbital theory at RHF/6-31G(d) and MP2/6-311G(d,p) levels. Three equilibrium structures and two isomeric transition states were locat ed. Based on the MP2/6-311G(d,p) calculations, harmonic frequencies of vari ous isomers were obtained and further single-point calculations were perfor med at the QCISD(T)/6-311G(d) and MP2/6-311+G(3df,2p) levels, respectively. G2(MP2) theory was used for calculations on energies. Isomerization paths for isomers were investigated by intrinsic reaction coordinate (IRC) calcul ations at MP2/6-311G(d,p) level. Changes (DeltaH and DeltaG) of thermodynam ic functions, equilibrium constant K(T), A factor and reaction rate constan t k of the isomerization reaction among isomers of H2SiNaCl were calculated and then thermodynamic and kinetic properties were analyzed. The stability , reactivity and existence of various equilibrium structures were also disc ussed in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.