Theoretical Study of the Addition of SiF2 and SiCl2 to Ethylene

Abstract

The additions of SiFz and Sic12 to ethylene have been studied using fourth order perturbation theory and the 6-31 1 Wd,p) basis set at geometries determined with second order perturbation theory. In contrast with earlier calculations on the analogous SiHz addition, found to proceed with no barrier, barrier heights of 18.4 and 4.5 kcallmol are predicted for the fluoro-and chlorosilylenes, respectively. These results are interepreted in terms of the net energetics, ring strain, and orbital properties. Disciplines Chemistry CommentsReprinted (adapted) Summary: The additions of SiFz and Sic12 to ethylene have been studied using fourth order perturbation theory and the 6-31 1 Wd,p) basis set at geometries determined with second order perturbation theory. In contrast with earlier calculations on the analogous SiHz addition, found to proceed with no barrier, barrier heights of 18.4 and 4.5 kcallmol are predicted for the fluoro-and chlorosilylenes, respectively. These results are interepreted in terms of the net energetics, ring strain, and orbital properties.

Computational study of reaction pathways in the course of interaction of deactivated silylenes with buta-1,3-diene

“…Thus, formation of VS from SiCl 2 and buta-1,3-diene requires overcoming much smaller reaction barrier and is more exothermic, than the analogous reaction of SiF 2 . This observation conforms with previous study of (2 þ 1) cycloaddition of SiF 2 and SiCl 2 to ethylene at the MP4/6-311G(d,p)//MP2/6-31G(d) level by Gordon and Nelson [28], where activation barriers of 77 and 19 kJ/mol were found for SiF 2 and SiCl 2 , respectively, and DE þ ZPE values are of À59 and À85 kJ/mol for the corresponding siliranes.…”

Direct Gas-Phase Kinetic Studies of Silylene Addition Reactions: SiH2 + C3H6, SiH2 + i-C4H8, and SiMe2 + C2H4. The Effects of Methyl Substitution on Strain Energies in Siliranes

“…230 kJ mol -1 , even larger than any of the values in Table . Other work which indirectly adds support is the theoretical study by Gordon and Nelson of the energetics of addition of SiCl 2 and SiF 2 to C 2 H 4 . The calculations indicate, among other things, that the two ring products, 1,1-dichlorosilirane, and 1,1-difluorosilirane, possess ring strain energies of ca.…”

Gas‐Phase Kinetics of Chlorosilylene Reactions II. ClSiH + C2H4: Absolute Rate Measurements and Quantum Chemical and RRKM Calculations for the Prototype π Addition Reaction

“…The enthalpy value of À88 kJ mol À1 obtained here for the formation of 1,1-dichlorosilirane (Table 3), is in good agreement with a value of À85 kJ mol À1 (MP4/6-311G(d,p) level) obtained by Gordon and Nelson. [42] The important point is that the cycloaddition of SiCl 2 is a further 50 kJ mol À1 less exothermic than that of ClSiH. SiCl 2 respectively.…”