Ab initio molecular orbital investigation of the unimolecular decomposition of CH[sub 3]SiH[sub 2][sup +]
- Iowa State Univ., Ames, IA (United States) Ames Research Lab., IA (United States)
- North Dakota State Univ., Fargo, ND (United States)
The potential energy surface for the decomposition of CH[sub 3]SiH[sub 2][sup +] was studied by ab initio electronic structure theory. At the MP2/6-31G(d,p) level of theory, CH[sub 3]SiH[sub 2][sup +] is the only minimum energy structure on the SiCH[sub 3][sup +] potential energy surface. Lower levels of theory reported that [sup +]CH[sub 2]SiH[sub 3] was also a local minimum, about 40 kcal/mol higher in energy with only a small (ca. 1-2 kcal/mol) barrier for conversion back to CH[sub 3]SiH[sub 2][sup +]. However, at higher levels of theory, the C[sub s] structure of [sup +]CH[sub 2]SiH[sub 3] has an imaginary frequency, indicating that it is a saddle point rather than a local minimum on the potential energy surface. The 0 K reaction enthalpies for 1,1-dehydrogenation from silicon, 1,2-dehydrogenation, 1,1-dehydrogenation from carbon, and demethanation were calculated to be 30.2, 69.1, 107.3, and 45.3 kcal/mol, respectively. Activation energies (0 K) were calculated at the MP4/6-311++G(2df,2pd) level of theory with the classical barriers subsequently adjusted for zero-point vibrational energies. The 0 K activation energies for 1,1-dehydrogenation from silicon, 1,2-dehydrogenation, and demethanation are predicted to be 66.6, 72.7, and 73.0 kcal/mol, respectively. 52 refs., 5 figs., 2 tabs.
- OSTI ID:
- 6868179
- Journal Information:
- Journal of Physical Chemistry; (United States), Vol. 99:1; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CATIONS
DECOMPOSITION
DEHYDROGENATION
ELECTRONIC STRUCTURE
ORGANIC SILICON COMPOUNDS
SILANES
CHEMICAL ACTIVATION
COMPILED DATA
ENTHALPY
HARTREE-FOCK METHOD
MOLECULAR ORBITAL METHOD
SADDLE-POINT METHOD
THERMOCHEMICAL PROCESSES
CALCULATION METHODS
CHARGED PARTICLES
CHEMICAL REACTIONS
DATA
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
IONS
NUMERICAL DATA
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
SILICON COMPOUNDS
THERMODYNAMIC PROPERTIES
400201* - Chemical & Physicochemical Properties
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661300 - Other Aspects of Physical Science- (1992-)