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Pressure Dependence of Rate Coefficients for Formation and Dissociation of Pentachlorodisilane and Related Chemical Activation Reactions
Author(s) -
Noda Kaito,
Kunioshi Nílson,
Fuwa Akio
Publication year - 2017
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.21098
Subject(s) - chemistry , dissociation (chemistry) , transition state theory , atmospheric pressure , thermodynamics , potential energy surface , reaction rate constant , activation energy , rrkm theory , atomic physics , kinetics , classical mechanics , molecule , meteorology , physics , organic chemistry
Four entrance channels to the pentachlorodisilane (Si 2 HCl 5 ) potential energy well, namely, SiCl 2 + SiHCl 3 , SiCl 4 + SiHCl, Cl 3 SiSiCl + HCl, and SiCl 3 + SiHCl 2 , were analyzed in detail through transition state theory, Rice–Ramsperger–Kassel–Marcus (RRKM) theory, and solution of the multichannel master equation. The stationary points in the potential energy surface were optimized, and their vibrational frequencies and rotational constants calculated at the (U)B3LYP/6–31+G(d,p) level of theory; the (U)CCSD(T)/aug‐cc‐pVTZ level was then used for accurate estimation of activation energies. The pressure and temperature dependence of the rate coefficients of the channels related to Si 2 HCl 5 stabilization/dissociation was determined along a wide range of conditions, for the first time. All channels showed strong pressure dependence in the four cases, at least at low‐to‐moderate pressure conditions. Each entrance channel leads to the formation of different products under different conditions, and the mechanism was analyzed in detail. The results indicated that at atmospheric pressure the reactions are in the falloff region, and therefore do not support the adoption of high‐pressure limit rate coefficients in reaction models designed for simulation of systems at atmospheric or subatmospheric pressure conditions.