The construction of graph models for calculations of the properties of substitution isomers of basis structures on the basis of additivity of energy contributions

Abstract

A method for the construction of additive models for calculations of the properties of substitution isomers of basis structures is described for the example of a series of X-substituted methylsilanes CH3 − k X k -SiH3 − l X l (where X = CH3, F, Cl, …, k, l = 0, 1, 2, 3). The method is based on similarity of subgraphs in graphs of several molecules and the arrangement of polygonal numbers (triangular, tetrahedral) of the Pascal triangle. Parameters taking into account multiple nonvalence interactions (-C-Si C-Si<, …) through two atoms along the molecular chain of an X-substituted methylsilane (X = CH3) were for the first time explicitly included in the calculation scheme. Taking these interactions into account allows us to completely differentiate all the structural isomers of certain molecules and obtain numerical parameter values for predicting properties P under consideration in various approximations. Numerical calculations of Δf H g,298 K o were performed for 16 alkylsilanes (as X-substituted methylsilanes), including 7 compounds not studied experimentally.