Mechanism of Reactions of 1-Substituted Silatranes and Germatranes, 2,2-Disubstituted Silocanes and Germocanes, 1,1,1-Trisubstituted Hyposilatranes and Hypogermatranes with Alcohols (Methanol, Ethanol): DFT Study.

Denis Chachkov,Rezeda Ismagilova,Yana Vereshchagina

doi:10.3390/molecules25122803

Denis Chachkov, Rezeda Ismagilova + Show 1 more

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https://doi.org/10.3390/molecules25122803

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Journal: Molecules (Basel, Switzerland)	Publication Date: Jun 17, 2020
Citations: 8	License type: CC BY 4.0

Affiliation: Kazan Federal University

Abstract

The mechanism of reactions of silatranes and germatranes, and their bicyclic and monocyclic analogues with one molecule of methanol or ethanol, was studied at the Density Functional Theory (DFT) B3PW91/6-311++G(df,p) level of theory. Reactions of 1-substituted sil(germ)atranes, 2,2-disubstituted sil(germ)ocanes, and 1,1,1-trisubstituted hyposil(germ)atranes with alcohol (methanol, ethanol) proceed in one step through four-center transition states followed by the opening of a silicon or germanium skeleton and the formation of products. According to quantum chemical calculations, the activation energies and Gibbs energies of activation of reactions with methanol and ethanol are close, their values decrease in the series of atranes–ocanes–hypoatranes for interactions with both methanol and ethanol. The reactions of germanium-containing derivatives are characterized by lower activation energies in comparison with the reactions of corresponding silicon-containing compounds. The annular configurations of the product molecules with electronegative substituents are stabilized by the transannular N→X (X = Si, Ge) bond and different intramolecular hydrogen contacts with the participation of heteroatoms of substituents at the silicon or germanium.

Highlights

Heterocyclic compounds of hypervalent atoms, primarily intra-complex compounds of triethanolamine–metallatranes, possess unique physical and chemical properties that are due to their unusual trigonal-bipyramidal structure with a transannular nitrogen–element bond and the presence of an axial fragment
We studied reactions of series substituted atranes and their analogues with ethanol theof activation energythe decrease in the of atranes—ocanes—hypoatranes
The mechanism of reactions of 1-substituted silatranes and germatranes, 2,2-disubstituted silocanes and germocanes, 1,1,1-trisubstituted hyposilatranes and hypogermatranes with one ethanol molecule according to quantum chemical calculations is shown in Scheme 5

Summary

Introduction

Heterocyclic compounds of hypervalent atoms, primarily intra-complex compounds of triethanolamine–metallatranes, possess unique physical and chemical properties that are due to their unusual trigonal-bipyramidal structure with a transannular nitrogen–element bond and the presence of an axial fragment. Despite the the long long history history of of the the chemistry chemistry of of atrane atrane systems, systems, issues issues affecting affecting their their spatial spatial and and electronic structure, as well as the reaction mechanisms of these compounds, do not lose their electronic structure, as well as the reaction mechanisms of these compounds, do not lose their relevance, relevance, and the development of quantum contributes a lot These to this.new. These new and the development of quantum chemistrychemistry methods methods contributes a lot to this.

Structures

Reactions of 1-Substituted Atranes with Methanol

Conclusions