S. P. Kolesnikov

The isolation and x-ray crystal structure of Δ1,7 2,2,6,6-tetramethyl-4-thia-8,8-dimethyl-8-germabicyclo[5.1.0]octene; The first representative of germirenes

The first representative of germirenes, Δ1,7 2,2,6,6-tetramethyl-4-thia-8,8-dimethyl-8-germabicyclo[5.1.0]octene has been isolated and its X-ray crystal and molecular structure have been determined.

The first example of [2+2] cycloaddition of Me4Ge2 to multiple bonds. The synthesis of Δ1,7-2,2,6,6,8,8,9,9-octa-methyl-4-thia-8,9-digermabicyclo[5.2.0]Nonene

Abstract The first example of a [2+2] cycloaddition reaction of Me 4 Ge 2 with acetylene is described. A new derivative of 1,2-digermacyclobutene, namely Δ 1,7 -2,2,6,6,8,8,9,9-octamethyl-4-thia-8,9-digermabicyclo[5.2.0]nonene, is prepared.

Synthesis of the first germa-1-pyrazoline and its decomposition via a germirane intermediate

Abstract The first germapyrazoline, 4-germa-1-pyrazoline ( 2 ), has been obtained by [2 + 3] cycloaddition of diazomethane to the GeC bond of the germene ( 1 ). Thermal or photochemical decomposition of 2 via a germirane intermediate ( 4 ) gives 9-methylenefluorene and dimesitylgermylene, which can be trapped by 2,3-dimethylbutadiene.

Electron density distributions in substituted 2,3,4,5-tetraphenyl- 1-germacyclopenta-2,4-dienes studied by NMR spectroscopy

The signals in the13C NMR spectra of 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes (R1=R2=H, Me,cyclo-C3H5, SiMe3, SnMe3, R1=Me, R2=H, Cl) were completely assigned using 2D NMR spectroscopy. The pattern of the variation of the chemical shifts in the13C NMR spectra indicates that the effects of substituents R1 and R2 on the heterocycle and on the phenyl groups are of inductive rather than mesomeric origin and include the direct through-space polarization of bonds (field effect).

Etherates of Friedel-Crafts acids with a short hydrogen bond: Symmetrical [Et2O......OEt2]+ cation in the crystal structure of the etherate (Et2O)2·HZnCl3

Conclusions1.HMCln Friedel-Crafts acids (where M is Al, Zn, Ge, Sn, etc.) form (Et2O)2·HMCln etherates with diethyl ether. By their IR and1H and13C NMR spectra and x-ray diffraction patterns, these are compounds of similar structure with a short H bond in the cation.2.X-ray diffraction study of (Et2O)2·HZnCl3 established that its crystal consists of centrosymmetric [ZnCl6]2− dianions and [Et2O......OEt2]+ cations, without close contacts between them. The symmetrical O......O segment in the cation has an O...O distance of 2.394(4) A, which is one of the shortest for this type of H bond.

Proton-donor properties of HCCl3, HSiCl3, and HGeCl3 molecules: a quantum-chemical study

Proton-donor properties of HCCl3, HSiCl3, and HGeCl3 molecules were studied by quantum-chemical methods. According to calculations, the Mulliken charge of H is positive in trichloromethane and negative in the other two molecules. Trichlorogermane readily interacts with bases (B) to give the contact ion pairs HB+·GeCl3–. Reactions of trichlorosilane with strong bases also can lead to its reorganization and the formation of contact ion pairs. In all the ion pairs, the anions are oriented to the HB+ cations by the negatively charged Cl atoms. Owing to possible transfer of Cl– to HB+, this type of ion pairs can be a source of dichlorogermylene GeCl2 and, probably, dichlorosilylene SiCl2.

13C NMR study of 2,3,4,5-tetraphenylsilole dilithium salt

The complete assignment of the signals in the13C NMR spectra of 2,3,4,5-tetraphenyl-1-R1,R2-1-silacyclopenta-2,4-dienes (R1=R2=H, Me) and of the dianion of lithium salt [(PhC)4Si]2−·2Li+ was carried out by 2D NMR spectroscopy.

Crystal and molecular structures of three germylated steroids

Germylated steroids were studied by X-ray diffraction analysis for the first time. The conformational parameters of the molecules in the crystals are discussed. The three-center hypervalent O−Ge−Cl bonds are observed in two β-isomers. The geometric parameters of the hypervalent units are compared.

Correlation NMR spectroscopy of 1,1-dichloro-2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-diene

Assignment of all of the signals in the1H and13C NMR spectra of 1,1-dichloro-2,3,4,5-tetraphenyl-l-germacyclopenta-2,4-diene has been carried out using two-dimensional NMR spectroscopy.

NMR study of diastereoisomerism of 2-(1-aminoethyl)bicyclo[2.2.1]heptane and its hydrochloride (deitiforin)

The assignment of the signals for the H and C atoms of four diastereomers (without their separation) of 2-(1-aminoethyl)bicyclo[2.2.1]heptane (1) and its hydrochloride (2) (the antiviral drug deitiforin) was performed for the first time by two-dimensional 1H and 13C NMR spectroscopy. The effects of the substituent at position 2 of norbornane on the chemical shifts of the α-, β-, and γ-carbon atoms of the bicycle were examined using the increments for alkanes. The changes in the chemical shifts of the C(6) and C(7) atoms are substantially larger than those for the other C atoms, which made it possible to identify the exo and endo forms. Each of these forms exists as a mixture of two diastereomers. The effect of the positive charge of the N atom on the γ-protons, which are closely spaced, but separated by a number of covalent bonds, was considered on going from amine 1 to hydrochloride 2. Based on significant changes in shielding of these H atoms, the configurations of the asymmetric center in the CHMe(NH2) substituent of the diastereomers were established.