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 located. Based on the MP2/6-311G(d,p) calculations, harmonic frequencies of various isomers were obtained and further single-point calculations were performed 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) calculations at MP2/6-311G(d,p) level. Changes (DeltaH and DeltaG) of thermodynamic functions, equilibrium constant K(T), A factor and reaction rate constant 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 discussed in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.