O. A. D'yachenko

An x-ray diffraction structural analysis of 1,1-bi(1-α-naphthyl-1-silacyclobutyl), the first monosilacyclobutane derivative with an Si-Si bond

Conclusions1.The molecular and crystal structure was found for bi (1-α-naphthyl-1-silacyclobutyl), the first monosilacyclobutane derivative containing an Si-Si bond. The silacyclobutane fragment has almost planar conformation with slight differences in the C-C bond lengths.2.A comparison of the geometric configuration of silacyclobutanes indicates that their Si...β-C distances are characteristically constant. This invariance is achieved by variations in the ring flexure angle ϕ and in the endocyclic CCC bond angle, which are related by a linear equation.

Ethyl 4-thi0cyanato-3-oxo-2-arylhydrazono-1-butanoates in heterocyclization reactions

ConclusionsSubstituted 1,3-oxathiolanes or substituted 2-chloro-1,3-thiazoles are formed in the reaction of ethyl 4-thiocyanato-3-oxo-2-arylhydrazono-1-butanoates with gaseous HCl in absolute benzene, depending on the electron-donor properties of the substituents in the arylhydrazone.

Novel synthesis, structure, and properties of 3-aryl-4-thiono-6-cyano-7-aryliminothiopyrano[2,3-d]pyrimidines

ConclusionsA simple, one stage synthesis of the previously inaccessible 3-aryl-4-thione-6-cyano-7-aryliminothiopyrano[2,3-d]pyrimidines has been proposed from cyanothioacetic acid arylamides RC6H4NHCSCH2CN (R=H, p-CH3, p-Cl) and orthoformate ester by heating at 110–120°C.

Structure of 3,4-dinitro-3,4-dimethyl-1,1-diphenyl-1-silacyclopentane

Conclusions3,4-Dinitro-3,4-dimethyl-1,1-diphenyl-1-silacyclopentane in the liquid phase has a half-chair conformation, and in the solid phase, its conformation is described by a form intermediate between the half-chair and the envelope conformation.

Structure of 1,1,3,3-bis(trimethylene)-1,3-di-α-naphthyldisiloxane

Conclusions1,1,3,3-Bis(trimethylene)-1,3-di-α-naphthyldisiloxane is a centrosymmetric dimer with a linear SiOSi group. The silacyclobutane fragment has a folded conformation with flexure angle ϕ=28.9°. The transannular Si...Cβ distance is 2.350(3) Å. The presence of an electronegative substituent (oxygen atom) at the silicon atom leads to a contraction of the Si-C bonds in the heterocycle to 1.863(2) Å.

Structure of 4-nitro-3-methyl-1,1-diphenyl-1-sila-2-cyclopentene

ConclusionsPMR spectroscopy and x-ray crystallographic structure analysis were used to study the structure of 4-nitro-3-methyl-1,1-diphenyl-1-sila-2-cyclopentene. The five-membered organosilicon heterocycle in the compound has envelope conformation with a ring flexure angle of 17.7°. A coordination interaction of the silicon atom with the NO2 group is excluded. The structural parameters do not indicate any additional interaction of silicon with the double bond.

Structure of 4-phenylamino-2-diethoxyphosphonyl-3-chloroquinoline

Conclusions1.On the basis of results obtained in an x-ray structure study of 4-phenylamino-2-diethoxyphosphony1-3-chloroquinoline, it was established that in the reaction of bis-arylimidoyl chlorides of dichloromalonic acid with triethylphosphite, 2-diethoxyphosphonyl derivatives of quinoline are formed.

Planar silicon-carbon heterocycle in dinaphthylsilacyclobutane

ConclusionsAs a result of an x-ray structure study of 1,1-di-α-naphthyl-1-silacyclobutane, a planar structure has been established for the first time for a four-membered silicon-carbon heterocycle.

Influence of chloromethyl substituent on structure and donor-acceptor properties of 10-methyl-10-chloromethylphenothiasiline

SummaryFrom an x-ray structure study of crystals of 10-methyl-10-chloromethylphenothiasiline, it has been found that the presence of the electron-acceptor substituent CH2Cl on the Si atom leads to destabilization of the heterocycle, an increase in nonplanarity of the molecule, and a weakening of its aromatic properties, both in the ground state and in the state with charge transfer.