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

• Published in: Journal of organometallic chemistry Vol. 695; no. 21; pp. 2345 - 2353
• Main Authors: Rynin, S.S., Faustov, V.I., Boganov, S.E., Egorov, M.P., Nefedov, O.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2010
• Subjects: (2 + 1) Cycloaddition; (4 + 1) Cycloaddition; [1,3]-Sigmatropic rearrangement; G3(MP2)//B3LYP; Siliranes; Silylenes; Silylenes; [1,3]-Sigmatropic rearrangement; G3(MP2)//B3LYP; (4 + 1) Cycloaddition; (2 + 1) Cycloaddition; Siliranes
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/j.jorganchem.2010.06.023

The PESs of systems including deactivated silylenes (SiHHal, SiHal
2, Hal
=
F, Cl, and 2-silaimidazol-2-ylidene, SiN
2H
2C
2H
2) and buta-1,3-diene have been studied using G3(MP2)//B3LYP method. Two major reaction channels, (2
+
1) and (4
+
1) cycloaddition reactions, leading to 2-vinylsiliranes and silacyclopent-3-enes, respectively, as well as [1,3]-sigmatropic rearrangements between 2-vinylsiliranes and the corresponding silacyclopent-3-enes, have been considered in detail. Reactivity of silylenes toward buta-1,3-diene decreases in the following series: SiHHal
>
SiHal
2
>
SiN
2H
2C
2H
2, which is reflected in increase of the reaction barriers for both cycloaddition reactions and in decrease of exothermicity of the formation of the corresponding products. The (4
+
1) cycloaddition is preferable for SiHal
2 and SiN
2H
2C
2H
2 and can compete with (2
+
1) cycloaddition for SiHHal. [1,3]-Sigmatropic rearrangement is important for isomerization of 2-vinylsiliranes to the corresponding silacyclopent-3-enes for all systems studied, except the SiCl
2 system.
The PESs of systems including deactivated silylenes (SiHHal, SiHal
2, Hal
=
F, Cl, and 2-silaimidazol-2-ylidene) and buta-1,3-diene have been studied using G3(MP2)//B3LYP method. The (2
+
1) and (4
+
1) cycloaddition reactions, leading to 2-vinylsiliranes and silacyclopent-3-enes, respectively, as well as [1,3]-sigmatropic rearrangements between 2-vinylsiliranes and silacyclopent-3-enes have been considered.
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