Establishment of correlations between the structure and reactivity of molecules in the gas phase based on information theory

A general approach to revealing correlations between the structure of molecules and their reactivity in fragmentation processes under electron impact conditions based on the use of generalized structural and mass spectral characteristics is suggested. The characteristics were obtained using information theory, molecular graphs, and absolute reaction rates. Information topological indices of molecular graphs were used as generalized structural characteristics of molecules. They are a quantitative measure of the structural complexity of molecules and are expressed in information units. The gas-phase process of fragmentation of molecules under electron impact was used as a general reaction series for all volatiles. In terms of information theory, the mass spectrum represents the distribution of probabilities of the formation of ions of each type, and the information entropy of this distribution appears to be an integral characteristic of the reactivity of a molecule during fragmentation under electron impact in the gas phase. Using organic and organometallic compounds of several classes (ferrocene derivatives, arylsilanes, aromatic azo compounds,etc.) as examples, linear correlations between the information indices of the mass spectra and the information topological indices of the appropriate molecular graphs or electronic parameters of molecules have been found, which testifies that the approach suggested is adequate.Translated fromIzvestiya Akodemii Nouk. Seriya Khimicheskaya, No. 11, pp. 2683–2688, November, 1996.