Tamara I. Vakul'skaya

1-[N-(2-Aminoethyl)aminoalkyl]silatranes and their complexes with CuCl2

Abstract 1-[ N -(2-aminoethyl)aminoalkyl]silatranes, NH 2 (CH 2 ) 2 NH(CH 2 ) n Si(OCH 2 -CH 2 ) 3 N (I, n = 1; III, n = 3) and their paramagnetic complexes with CuCl 2 (2 : 1) (III) and IV) have ben synthesized. Relevant 1 H and 13 C NMR data reveal, that the molecule I in the series of silatranes has the weakest transannular Si ← N bond. The pattern of the signals and the value of the g -factor in the ESR spectra of complexes III and IV in the crystaline state and in MeOH or DMSO solution points to distortion of the chelate planes and to conformational inhomogeneity. The fragmentation of complexes III and IV in Xe 0 fast atom bombardment (FAB) mass spectra indicates that the Si ← N bond in their molecules is stronger than those in the initial silatranes I and II.

Regio- and stereospecific addition of phosphines to cyanoacetylenes

Abstract Primary and secondary phosphines add regio- and stereospecifically to phenylcyanoacetylene and 4-hydroxy-4-methylpent-2-ynenitrile under mild conditions to form corresponding functionalized secondary and tertiary phosphines of Z -configuration in 70–91% yield. According to ESR and UV data, the addition of primary phosphines to phenylcyanoacetylene involves a single electron transfer process.

Vicarious Nucleophilic C-Amination of Nitrobenzene and 5- and 6-Nitro-1-methylbenzimidazoles

Vicarious nucleophilic C-amination of nitrobenzene, 1-methyl-5-nitrobenzimidazole, and 1-methyl-6-nitrobenzimidazole in superbasic medium (potassium tert-butoxide-dimethyl sulfoxide) gave the corresponding amino-substituted derivatives. The yield of the amination product of 1-methyl-5-nitrobenzimidazole considerably increased in the presence of CuCl. ESR monitoring of these reactions revealed formation of primary radical anions from the substrates. Possible reaction mechanisms are discussed.

ETHYNETHIOL-BASED POLYENEPOLYSULFIDES FROM ACETYLENE AND ELEMENTAL SULFUR: SYNTHESIS AND PROPERTIES

Ethynethiol-based polysulfide polymers [Cssize 2}H2S x ] (x = 1-6) have been synthesized by the reaction of sodium acetylides and elemental sulfur in liquid ammonia with the following hydrolysis of sodium ethynethiolates and spontaneous polymerization of ethynethiols thus formed. The polymers are brown powders (up to 87% sulfur content), possessing electroconducting (10−13–10−14 S · cm−1), paramagnetic (1018 spin · g−1) and redox properties. Application of the polymers as active cathode materials provides for a stable cycling of model lithium batteries. * Now Sion Power Corporation.

Vicarious C-amination of 1-methyl-4-nitroimidazole

A one electron transfer process during the vicarious nucleophilic substitution C-amination of 1-methyl-4-nitroimidazole is detected by EPR-monitoring.

Sulfurization of polymers

Polyethylene exhaustively sulfurized with elemental sulfur shows paramagnetic (spin concentration 2.7–9.7·1019 sp g−1,g=2.0041–2.0045, ΔH=0.53–0.62 mT) and redox properties, which was demonstrated by both voltammetric and chemical methods (sodium reduction in liquid ammonia). The high concentration of unpaired electrons, the character of the electrochemical activity, and the chemical properties are in agreement with the presence in the polymers of polyconjugated ladder polythiophene and parquet polynaphtho-thienothiophene structures along with polyene-polysulfide blocks. The use of the polymers under consideration as an active cathode material in lithium batteries enables their repeated cycling with a specific charge capacitance of 150–340 mA hg−1.

Pyrroles as C-nucleophiles in reactions with acylacetylenes

The reactions of substituted pyroles with terminal acylacetylenes occur selectively to form 2-(Z/E-2-acylvinyl)pyrroles. When the reactions are performed on the surface of silica gel,C-vinylation is noticeably accelerated to form predominantlyE-isomers. ESR spectroscopy with the use of a spin trap demonstrated the ion-radical character of the process. The structures of the adducts synthesized, which exist asanti-s-cis- andsyn-s-cis-rotomers, were studied by IR, UV, and NMR spectroscopy.

Tautomerism of 3-nitro-1,2,4-triazole-5-one radical anions

The non‐degenerate tautomers of 3‐nitro‐1,2,4‐triazole‐5‐one (NTO) radical anions were investigated for the first time by an ESR method during electrochemical reduction of NTO in an aprotic medium. Copyright

Nanocomposites of silver with arabinogalactan sulfate: Preparation, structure, and antimicrobial activity

Silver-containing nanocomposites based on sulfated arabinogalactan have been prepared under mild conditions. The products contain 2–12 nm silver nanoparticles stabilized by the polymer. The composites are readily water-soluble and reveal antimicrobial activity against a wide range of bacteria and fungi.

New Electrochemically Active Highly Sulfurized Polyconjugated Polymers

The electrochemical activity of new highly sulfurized polyconjugated polymers is studied. The polymers, polythienothiophene, poly(4,5,6,7-tetrathieno-4,5,6,7-tetrahydro-2,3-dehydrobenzothiophene), poly(6-methylthieno[2,3-b]pyridine-4-thione-5-thiol), and poly(6H-thieno[2,3-b]-azepine-6,7(8H)-dithione) are obtained in a deep sulfurization of polyethylene, polystyrene, and poly(5-vinyl-2-methylpyridine) by elemental sulfur. Employed as active cathodic material in lithium batteries, these polymers ensure their prolonged cycling with specific discharge capacity of up to 339 mA h/g. The effect of the conducting additive and electrolyte on the energy capacity and cycling of polymer cathodes in lithium batteries is discussed.