The use of the structural correlation method for the estimation of the quality of ab initio and DFT predictions of geometry parameters of related compounds in the gas phase and in solutions. An example of (O–Si)chelates with ClSiC 3O coordination center

Abstract

X-ray data on the intramolecular complexes 1– 4 ( N-dimethylchlorosilylmethyl derivatives of amides, lactams, carbamides, and hydrazides of carbon acids) possessing an identical ClSiC 3O coordination center have been used for mapping the path of the S N2 substitution reaction at Si IV with the Bürgi–Dunitz method. A classic hyperbolic like representation of the reaction coordinate has been obtained using the nonlinear least squares method. The hypothesis of the unified character of the change in geometry parameters of the ClSiC 3O reaction center in 1– 4 under the influence of internal factors and the medium is corroborated based on the study of ab initio and DFT gas-phase and solution structures of a series 1– 4. The extent of deviation of calculated points from the correlation function, defined by the collective body of X-ray data for the coordination center of related compounds, may be used as an indicator of the accuracy of their geometry calculation in the isolated state and, especially, in solutions.