V. N. Urazbaev

Relationship between the Stereospecificity of Lanthanide Catalysts and the Structures of Active Sites and Dienes, the Nature of a Cocatalyst, and Preparation Conditions

Several types of active sites can be formed during the polymerization of dienes in the presence of lanthanide catalytic systems. These sites differ in the nearest environment of a lanthanide atom (the numbers of chlorine and carbon atoms) and in the number of lanthanide–carbon bonds involved in chain growth. Quantum-chemical calculation shows that the π-allyl binding of the terminal unit of a growing polymeric chain with the lanthanide atom of an active site may be the reason for the cis-stereospecificity of the site. Therefore, the active sites containing electron-acceptor chlorine atoms that favor π-allyl binding can form cis-polydienes. Depending on the conditions of catalytic system preparation, primarily on the nature of an organic compound of a nontransition metal, one or another set of active sites is formed that can affect its stereospecificity. The quantitative analysis of kinetic data for diene polymerization shows that the anti-synisomerization of terminal units of growing polymeric chains made a certain contribution to the formation of trans-1,4 units in the presence of cis-regulating active sites.

Reactivity indices of adamantane-containing diamines in the synthesis of polyimides

The reactivity of adamantane-containing diamines in the reactions with dianhydrides of 3,4,3′, 4′-tetracarboxydiphenyl oxide was studied as a function of the parameters of their electronic structures. It was found that the reactivity changes in parallel with the charges on the N atoms, the energy of homolytic cleavage of the N-H bond, and the basicity of diamines.

Reactions of Grignard reagents with 1,3-dicyanoadamantane

Reactions of Grignard reagents RMgX (R = Me, Et, Pr, Bu; X = Br, I) with 1,3-dicyanoadamantane (1) were studied. Optimum conditions for the synthesis of monoaddition products of Grignard reagents to compound 1 were established. The first stage of the reaction of cyanoadamantane 1 with MeMgBr was studied by the MNDO-PM3 method. According to calculations, the more preferable reaction mechanism involves formation of a six-membered cyclic intermediate containing two Mg atoms, two C atoms, and one Br and one N atom.

Experimental and quantum-chemical investigation of thermolysis of adamantyl-substituted organosilicon peroxides

The kinetics and mechanism of thermal decomposition of adamantyl-containing organosilicon peroxides in a solution inn-nonane were studied. The relationship between the structure of the peroxide and the rate and mechanism of thermolysis was established. The effect of the peroxide structure on the electronic characteristics of the peroxide bond was studied by the MNDO method. The heterolytic rearrangement occurring during the decomposition of peroxides was analyzed.

Electronic structure of active centers and kinetic stereocontrol in polymerization of butadiene under the influence of a catalytic system based on neodymium chloride

On the basis of quantum-chemical calculations of models of active centers, a suggested mechanism of kinetic stereocontrol of the microsctructure in polymerization of butadiene under the influence of the catalytic system NdCl3 · 3TBP-HA1 (i-C4H9)2 has been verified experimentally.