A DFT study on the thermal decomposition of 2-chloroethylsilane

• DOI: 10.1007/s11224-012-9962-9
• Publication Date: 2012-02-15T07:00:10Z
• Authors: Yiling Bei; Qingyang Liu; Shengyu Feng
• Keywords: Chlorosilane; Transition state theory; Transition state; Atmospheric temperature range

The thermal decomposition of 2-chloroethylsilane (H3SiCH2CH2Cl) was investigated by density functional theory (DFT) method at the B3LYP/6-311G(d,p) level. The structures of reactants, transition states, and products were located and fully optimized at the B3LYP/6-311G(d,p) level, and the geometries of various stationary points and harmonic vibrational frequencies were calculated at the same level. The reaction paths were investigated and confirmed by intrinsic reaction coordinate calculation at the B3LYP/6-311G(d,p) level. The results showed that the thermal decomposition of 2-chloroethylsilane could happen in one pathway. The chlorine migrated with negative charge from the β-carbon toward the silicon resulting in the Cβ–Cl bond dissociated, then the Cα–Si bond length increased passing through a four-centered transition state to form chlorosilane (H3SiCl) and ethene (CH2=CH2). The B3LYP/6-311G(d,p) barrier for the decomposition reactions was 177.0 kJ mol−1. The halogen-substituent effects on 2-chloroethylsilane showed that the less negative charges on β-carbon atoms made the reaction more likely to occur. Changes in thermodynamic function, equilibrium constant, and reaction rate constant in Eyring transition state theory were calculated over a temperature range of 400–1,500 K.