DETERMINATION OF THE ARRHENIUS PARAMETERS FOR SI2H6 REVERSIBLE-ARROW SIH4 + SIH2 AND DELTA-H-CIRCLE-F(SIH2) BY RRKM ANALYSIS OF FORWARD AND REVERSE REACTION-RATE DATA

Arrhenius parameters for disilane dissociation are estimated by direct regression of RRKM-derived predictions of experimental data for both the forward unimolecular and reverse association reaction. Laboratory kinetic data spanning a wide range of temperatures (300-1005 K) and pressures (1-2500 Torr) were employed to find a predictive RRKM model. The model was further fit by the empirical F(cent) method to yield a facile computational model for accurate prediction of the rate coefficient over a wide range of experimental conditions. The high pressure Arrhenius expression, log k(T) = (15.78 +/- 0.30) - (52.07 +/- 0.75) kcal mol-1/2.3 RT at 500 K, is recommended. The best fit value of DELTA-H-degrees(f,298)(SiH2), which was treated as a parameter in the regression procedure based on the disilane reaction alone, was 64.4 +/- 1.0 kcal mol-1, with the major source of uncertainty being in the temperature extrapolation of the high pressure rate constants.