Studies on the Thermodynamic and Kinetic Properties of the Reactions of Ti+ with Sulfur Transfer Reagent SCO Along the C═S Bond Activation Branch at 200–1200K

Abstract

Theoretical studies on the thermodynamic and kinetic properties of the reactions of Ti+ with sulfur transfer reagent SCO via the C═S bond activation pathway have been carried on using DFT/B3LYP method, general statistical thermodynamics, and Eyring transition state theory with Wigner correction. The relevant reactions include reaction 1 4 Ti++1SCO → 4 IM 1 → 4 TS 1 → 4 IM 2 → 4 TiS++ 1 CO, and reaction 2 4Ti++1SCO →4IM1→ CP →2IM2→2TiS++1CO in which the spin multiplicity changes from the quartet state to the doublet state in the crossing region. It is concluded that the increase of the temperature is favored to the reaction 1 process, since the equilibrium constants (K) rises from 0.566 × 10[P]-9 at 200 K to 0.109 × 100 at 1200 K, and the reaction rate constant (k) from 0.222 × 100 s[P]-1 at 200 K to 0.540 × 10 11 s[P]-1 at 1200 K. Moreover, reaction 1 is endothermic, and non-spontaneous in the way the entropy increases, while reaction 2 is exothermic and spontaneous in the way their entropy decreases. The reaction path 2 is the energetically favorable channel, and its thermodynamic data change not largely with the rise of temperature.