Now a model of 3-center 4-electron bonds (N→Si−R, N→Ge−R) is more recognized for the description of atrane systems, which is confirmed by the data of modern quantum chemical calculations. Other atoms of the heterocyclic frame can participate in stabilization of the endo-configuration of atranes or ocanes. We performed a theoretical study of the hydrolysis reactions of 2,2-disubstituted silo- 1-8 and germocanes 9-16, and 1-substituted sila- 17-22 and germatranes 23-28 by the method DFT B3PW91/6-311++G(df,p) (Scheme). The calculations of all reactants were carried out, and all elementary steps were found. The structures localized on the potential energy surface were identified as minima or transition states by calculating the corresponding Hessian matrices. In all cases, the descents from transition state in the direction of the initial molecule and in the direction of the reaction product were performed for the confirmation of conformity of the found structure of transition state for the studied reactions of hydrolysis. The calculations were performed without taking into account the solvent. According to the data of quantum chemical calculations, the molecules of 1-28 initially form pre-reaction complexes with the water molecules, transforming into the transition states, which as a result of the breaking of Si–O2 or Ge–O2 bond are converted into the hydrolysis products. The hydrolysis reactions for 1-28 are controlled by the thermodynamic factors. The ring configurations of the hydrolysis products are stable due to the presence of dative interaction N→X (X = Si, Ge) and intramolecular hydrogen bond in their molecules. Both spatial factor (the length of N→Si or N→Ge bond) and the presence of electronegative substituents at the acceptor silicon or germanium atom testify to a possibility of transannular interaction N→Si (N→Ge). Features of the structure of reagents and products, details of the mechanism of hydrolysis reactions established will be discussed.

Mechanism of hydrolysis reactions of 2,2-disubstituted silo- and germocanes, 1-substituted sila- and germatranes

254th National Meeting (2017)

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