V. I. Baranovskii

Thermochemical Study of Gaseous Salts of Oxygen-containing Acids: IX. Calcium and Strontium Metaborates

Vapor formation in the systems CaO-B2O3 and SrO-B2O3 was studied by high-temperature mass spectrometry. Equilibria involving gaseous calcium and strontium metaborates were studied. Standard enthalpies of formation and atomization of the molecules CaB2O4(gas), CaBO2(gas), SrB2O4(gas) and SrBO2(gas) were determined.

Chemistry of Ruthenium Polypyridine Complexes: IV. Quantum-Chemical Simulation of the Effect of Solvation Shell on the Electronic Structure of Ru(II) Complexes with Nitrogen-containing Ligands

Ab initio quantum-chemical calculations of Ru(II) complexes have been fulfilled with consideration for solvation within the framework of the polarized continuum model. Energy levels of fragments of Ru(II) complexes with organic ligands are shifted relative to each other by electrostatic interactions with the solvation shells.

Ab Initio calculation of molecular, thermodynamic, and kinetic parameters of CF, CF2, CF3, and C2F5 radicals and CF4, CF3I, C2F4, and C2F6 molecules in gas

Enthalpies of formation of ground states of the gaseous particles CF, CF2, C2F5, CF4, CF3I, C2F4, and C2F6 were calculated by ab initio method in the CCSD(T) approximation with extrapolation to the full basis and regard to the correlation energy. Their equilibrium geometrics, frequencies of normal vibrations, and other values were found by the B3LYP/aug-cc-pvdz method, from which thermodynamic functions within the range of 0–6000 K were calculated. Equilibrium constants were calculated from these functions, and then the information on the rate constants in the limit of high pressures was obtained.

Quantum-chemical simulation of the gas-phase molecular, thermodynamic, and kinetic parameters of CF, CF2, and CF3 radicals and CF4, C2F2, C2F4, and C2F6 molecules

Enthalpy of formation of gaseous CF, CF2, CF3, CF4, C2F2, and C2F4 molecules in the ground state have been simulated via the ab initio method in the CCSD(T) approximation with extrapolation to full basis and correlation energy. Equilibrium geometry, frequency of normal vibrations, and other parameters of these molecules have been determined; their thermodynamic functions at 0–2000 K were calculated from these data. Constants of the C2F6←→ 2CF3, C2F2←→ 2CF, C2F4←→ 2CF2, CF4←→ CF3 + F, CF4←→ CF2 + F2, and CF3←→ CF2 + F equilibriums have been calculated, and the data on the rate constants in the high-pressure limit have been obtained.

Photochemistry of XXI century: Paradigm change

The process of revision of the mechanisms of photochemical reactions is reviewed. The revision is characterized by the recognition of the role of conical intersections of potential surfaces in the transitions from excited to ground state. We may assume that, to date, this revision is completed.

Quantum-chemical method for determination of effective structure-energy parameters of multiparticle interaction in solutions of polar substances

A new method is developed for the determination of equilibrium value of effective structure-energy parameter of multiparticle interaction (Onsager radius of a molecule) in solutions of polar compounds. The method is based on the results of quantum-chemical calculations of the dependence of an electric dipole moment of the studied molecule in the ground state on the dielectric properties of the individual solvents that are applied. Additinal data were obtained that confirmed an opinion that by its physical sense the Onsager radius of a molecule was a value close to van der Waals radius of the same molecule which can be found using known methods of quantum chemistry and structural chemistry for isolated molecules (gas phase). It was shown by an example of solutions of 4-dimethylaminochalcone and several phthalimide and N-methylphthalimide derivatives that the results of determination of Onsager and van der Waals radii of all the studied molecules using three independent methods are in good quantitative agreement confirming their validity.

Role of carbon clusters in pyrolysis of iodomethanes

Molecular parameters and thermodynamic functions of the carbon cluster cyclo-C12 were calculated by the B3LYP method in the aug-cc-pVDZ basis. The composition of products of iodomethane pyrolysis in the range 500–1000 K was calculated from the data obtained in combination with published data on thermodynamic function of other molecules. High experimental yield of methane and carbon (carbyne) in the iodomethane pyrolysis and the absence of even traces of ethane, 1-iodoethane, and 1,2-diiodoethane were accounted for.

Quantum-Chemical Study of the Equilibrium Geometry and Electronic Structure of the Defensin Molecule

The molecular geometry of rabbit NP-1 defensin is fully optimized by means of molecular mechanics and MNDO methods. Atomic charges are calculated, and an estimate for the dipole moment of the molecule is obtained (μ 4.0 D). The possible mechanism of defensin-receptor interactions is discussed.

Quantum-Chemical Study of the Electronic Structure of the Complex Ions [Ru(NH3)5pyz]2+ and [Ru(CN)5pyz]3- in Solution

The hydration shell of the complex ions [Ru(NH3)5pyz]2+ and [Ru(CN)5pyz]3- was simulated on the basis of ab initio Hartree-Fock calculations in the supermolecular approximation, within the framework of the multicavity polarizable continuum model. In calculations of the spectral characteristics of complexes with a pronounced nonuniformity of electron density distribution, it is primarily necessary to take into account the shift of energy levels of particular fragments under the action of the electrostatic potential produced by the solvation surrounding. Consideration of the charge transfer between the complex and the outer-sphere water molecules has no significant effect on the calculated electronic spectrum; the transferred electron density is below 1e.

Valence Structural Analysis of the Metal-Ligand Bond in the {RuNO}6 Group

The electronic structure of complexes [Ru(XY)L5]q (L = NH3, Cl-, CN-; XY = NO, CO, N2) was represented as a combination of valence schemes based on ab initio and semiempirical quantum-chemical calculations. It was found that schemes corresponding to a covalent π bond between Ru(III) and NO contribute most in the case of the complexes containing a {RuNO}3+ group, which makes possible the nitroso ligands in these compounds to be considered as uncharged NO molecules. The necessity of inclusion of electron correlation in the description of π interactions between the metal and ligands was shown.