Thermodynamic and kinetic investigations of silathioformohydroxamic acid conformers

The Silathioformohydroxamic acid conformers were studied in the gas phase by a high level density functional theory. The global isomeric structure was S2 at the CBS-Q levels of theory. The stability order for the conformers were 1E>1Z>4Z>2Z>2E>3Z>S1. Thirteen anions and seven cations of various conformers have been studied. The protonation and deprotonation reactions in the gas phase are investigated at the CBS-Q level. The 2EOA showed the highest relative enthalpy and Gibbs free energy (ΔH= 249.57 kJ/mol, ΔG=240.62 kJ/mol) in the anions section and the 4ZOC showed the highest relative enthalpy and Gibbs free energy (ΔH= 285.12 kJ/mol, ΔG=234.13 kJ/mol) in the cations section. Energetically easiest process is the deprotonation of 2ZNA with the computed enthalpy and Gibbs free energy of 1274.52 kJ/mol and 1282.49 kJ/mol. The equilibrium constants at 298.15 K of the deprotonation reactions are very small which means the reaction at this temperature favor the reactants.

Author(s): Abdulhakim A. Ahmed

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