Raman Scattering Study of Natural and Synthetic Compounds Containing Polyene Chains

Doklady Physics - The dependence of Raman spectra of the molecules containing polyene chains on the conjugation length, structure of side and end groups, and isomer type is analyzed theoretically.     

Catalytic reactions of hydrocarbons promoted by coordination unsaturated Zr and Ti compounds: A density functional theory study

The paper is a review of a series of publications devoted to a number of homogeneous and heterogeneous catalytic reactions, their mechanisms, and energy characteristics. These reactions are promoted by coordination unsaturated compounds of Ti and Zr and proceed with cleavage and/or formation of C-C and C-H bonds in the hydrocarbon chain (polymerization reaction of ethylene, styrene, and butadiene-1,3, hydrogenolysis and hydroisomerization of linear and branched alkanes, and H/D isotope exchange in alkanes). A high-level quantum chemical method (DFT, PBE functional, gauss type TZ2p basis sets, the original PRIRODA program) was applied for the catalytic systems under the study. The nature and the structure of the active center, detailed mechanisms, and energy profile of the reaction of the substrate with a catalytic particle are considered. We compare our data with the results of both experimental and theoretical contributions from other authors.     

Regioselectivity of acid-catalyzed cyclization of 1-(3,4-dialkylaryl)-3-chloropropan-1-ones to indanones. Comparison of experimental data and results of computer simulation

The acid-catalyzed cyclization of 1-(3,4-dialkylaryl)-3-chloropropan-1-ones to dialkylindanones via the intermediate formation of (3,4-dialkylaryl)propenones was studied. This reaction affords isomeric products: 5,6-dialkylindan-1-ones and 4,5-dialkylindan-1-ones. The DFT quantum chemical calculation results correlate with the experimental data and suggest that the structural factors affect the ratio of products.     

Primary isotopic effect on the magnetic shielding of tin nuclei (117Sn and 119Sn)

The Kirkwood-Buff statistical mechanical theory of surface tension γ for monatomic fluids is extended to molecular fluids. A rigorous expression for γ is derived in terms of the angular pair distribution function f(z ₁ R ₁₂θ₁θ₂) of an equilibrium fluid-fluid system (liquid-gas, liquid-liquid, or gas-gas). The Fowler approximation is applied for the liquid-gas case, and a simple expression for γ is derived in terms of the bulk liquid angular pair correlation function g(R ₁₂θ₁θ₂). Thermodynamic perturbation theory for g(R ₁₂θ₁θ₂) is also used to calculate γ theoretically. The theoretical results are compared with experimental values.     

Redox induced reactions of transition metal π- and σ,π-complexes

In this review, redox-induced reactions of π- and σ,π-complexes leading to the selective formation (or cleavage) of C–H, C–C, and C–O bonds have been summarized. To illustrate the synthetic potential of such methodology, the following representative reactions studied in our group are discussed: (1) oxidatively induced hydrogen elimination from “open” cyclic diene and dienyl complexes resulting in formation of “closed” dienyl and arene complexes, respectively; (2) reductive activation of C–H bonds in diene, vinylidene, and carbyne complexes forming new multiple C–C bonds; (3) oxidative dehydrodimerization of vinylidene complexes into binuclear μ-divinylidene species; and (4) oxidatively induced addition of oxygen nucleophiles to μ-divinylidene complexes affording cyclic μ-dicarbene derivatives. Oleg V. Gusev, deceased on October 31.     

Synthesis and anion binding properties of 2,5-diamidothiophene polypyrrole Schiff base macrocycles

[reaction: see text] Two easy-to-synthesize polypyrrolic 2,5-diamidothiophene Schiff base macrocycles are reported, along with their anion binding properties as determined via UV-vis spectroscopic titrations carried out in dichloroethane. There is a striking difference between the interactions with anions of the two macrocycles, a finding ascribed to differences in their rigidity. For example, the more flexible dipyrromethane-derived macrocycle displays a 1.2:1 hydrogen sulfate versus nitrate selectivity, while its more rigid bipyrrole-derived congener shows a 7.4:1 selectivity in favor to hydrogen sulfate.