Ukhta State Technical University, Ukhta
Considering significance, a new important method of chemical research such as quantum-chemical calculation, which allows to predict geometrical structure, energy and other properties of the known and unknown molecules is compared to nuclear magnetic resonance (NMR). It should be noted that quantum-chemical research increases the number of chemical compounds not confined only to the synthesized one.
All calculations were performed on the program Gaussian03 . This pro-gram predicts the energies, molecular structures, vibrational frequencies and molecular properties of molecules and reactions in a wide variety of chemical environments. Gaussian 03’s models can be applied to both stable species and compounds which are difficult or impossible to observe experimentally (e.g., short-lived intermediates and transition structures).
Kinesthetic and thermodynamic characteristics of elementary reactions of gas phase thionyl chloride (SOCl2) hydrolysis, when mixed with water clusters, were calculated with the help of quantum chemical method DFT. The assumed mechanism included formation of the SOCl2 water dimers complexes, in which S-Cl bond hydrolysis took place. Molecular geometry optimization (search for transient state) was carried out according to the density functional theory (B3LYP/6-311++G(2d, 2p)). For the elementary reactions of hydrolysis, the transient states were determined and the activation energy was evaluated. The results show that water dimers considerably reduce the activation energy and boost hydrolysis process.
Moltran is a program for inspection of results after quantum chemical calculations performed with different quantum chemical packages including Gaussian and GAMESS. It also allows editing molecular structure working as a molecular builder. During the molecular editing, you can save or retrieve the molecular fragments to the database and use them later to create more complicated structures. A special feature of Moltran is a possibility to perform various thermodynamical calculations (with a broad variation of model parameters), taking into account the internal rotations if they are present in the molecule.