Formation of spiro-substituted 1,3-dithiolanes and thiiranes in the reaction of 3-aminoindene-1-thiones with aliphatic diazo compounds

3-Aminoindene-1-thiones react readily with diazomethane to give the corresponding 4,4;5,5-dispiro-substituted 1,3-dithiolanes. The production of both 2,2-spiro-substituted thiiranes and products of desulfuration of the latter is possible in the reaction of 3-aminoindene-1-thiones with substituted diazomethanes. The thermolysis, hydrolysis, and salt-forming reactions of the compounds obtained were investigated.Communication VIII from the series , -Unsubstituted Thio Compounds. See [1] for communication VII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 36–42, January, 1978     

Configuration of 2-substituted 1-aminoethyleneimines

The trans configuration of 2-phenyl- and 2-methyl-1-aminoethyleneimine was proved by means of their PMR spectra in the presence of tris(dipivaloylmethanato)europium.     

Ethylenimine chemistry

2-Methyl-N-aminoethylenimine was synthesized by the classic Wenker method and by amination of 2-methylethylenimine with hydroxylamine-O-sulfonic acid in alkaline media. NMR spectroscopy indicated the formation of exclusively the trans-inverted isomer, the pyramidal stability of the heteroatom of which, as in N-aminoethylenimine [3–5], is preserved over a broad range of temperatures. The hydrazones of N-aminoethylenimine are characterized by an appreciably lower pyramidal stability of the nitrogen than that associated with participation of its unshared electron pair in p, conjugation with the electrons of the C=N bond. The inversion barrier in the hydrazones decreases symbatically with an increase in the degree of the indicated interaction. However, the decrease is insufficient to freeze free rotation about the nitrogen-nitrogen bond up to –80.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 45–48, January, 1971.See [1] for communication VI.     

Silicon-nitrogen bonding in silatranes: assignment of photoelectron spectra

Silicon-nitrogen bonding and the photoelectron spectra of hydro-silatrane and methyl-silatrane, XSi[OCH2CH2]3N (X = H and Me), were studied with ab initio electron propagator theory, many-body methods, and density functional models. A linear vibronic coupling (LVC) model was employed to estimate vibrational widths of the ionization bands and to study the dependence of the ionization energies on the molecular geometry. Particular attention was given to coordinates that change the Si-N distance and the strength of the donor-acceptor interaction between these two atoms. The ionization energy of the highest occupied molecular orbital has a very strong geometrical dependence which leads to an unusually large vibrational width in the corresponding photoelectron band. The assignment of this band in methyl-silatrane, which was controversial for a long time, is resolved by the present study. The calculated photoelectron spectra allow for clear assignment of at least three more bands in the observed spectra. The present results demonstrate the important role of electrostatic interactions in Si <-- N bonding and in the outer-valence ionization energies of the silatranes.     

Quantum-chemical study of pentacoordinated silicon compounds: Si-substituted (O−Si) dimethyl(N-acetylacetamidomethyl)silanes

The mechanisms and self-consistency of the changes in geometric parameters, charge distribution, orbital structure and energy of the “soft” coordination center XSiC₃O in Si-substituted (O−Si)dimethyl(N-acetylacetamidomethyl)silanes upon variation of the nature of the substituent X (X=OCOCH₃, OCOCF₃, F, Cl, Br, I) have been established by the PM3 method. They have been found to be in complete correspondence with the experimental data and the hypervalent bonding model. In contrast to the prediction of the standard donor-acceptor complex model, a decrease in the ionization potential of the donor upon the formation of the 3c−4e XSi←O bond has been demonstrated. Significant shortcomings of the PM3 method in quantitative estimations of the complexation energy and the gas-phase geometry have been pointed out. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 230–235, February, 1998.     

Atranes

The dipole moments of the Si(OCH₂CH₂)₃N heterocyclic framework were calculated within the framework of an additive scheme by means of data from x-ray diffraction and conformational analysis of silatranes. The direction of the dipole moment of this fragment coincides with the “experimentally” determined value (from nitrogen to silicon), and its magnitude is ～3 D. The dipole moment of the Si ← N coordinate bond was estimated to be 2.2 D, which corresponds to charge transfer from the nitrogen atom to the silicon atom (to the extent of 0.2 e). These results refute the existing concepts of the exceptionally high polarity of the transannular Si ← N bond in silatranes.     

Study of some bis(silylmethyl)mercury compounds by the1H29Si,and199Hg NMR method

Conclusions On the basis of the NMR spectral data on¹H,²⁹Si, and¹⁹⁹Hg nuclei, it was shown that Hg-X coordination interaction is possible for the compounds (Me_3–nX_nSiCH₂)₂Hg, which is manifested to a greater degree for the chloro derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2139–2140, September, 1983.     

Proton-magnetic-resonance spectra of some organoethoxysilanes

The PMR spectra of 33 organoethoxysilanes have been investigated. Comparison of the chemical shifts of C₂H₅O and CH₃ groups attached to the silicon atom with the values of the remaining substituents at the central silicon atom gives reason to suppose that the contribution of each atom in p– interaction decreases with increased number of ethoxy groups at the silicon atom, while the over-all effect of increased electron density at the silicon heteroatom arising from this interaction increases. The Taft constants for several substituents are calculated.     

Si-Containing Amides of Phosphoric Acid

Summary. The first representative of the N-silylmethylamides of phosphoric acid O=P[NMe(CH₂SiMe _n (OEt)_3-n ]₃ have been synthesized by interaction of MeNHCH₂SiMe _n (OEt)_3-n (n = 2, 3) with POCl₃. The interaction of the N,N′,N″-trimethyl-N,N′,N″-tris[(ethoxydimethyl- silyl)methyl]triamide phosphoric acid with BF₃·Et₂O or BCl₃ results in the formation of the N,N′,N″-trimethyl-N,N′,N″-tris[(fluorodimethyl-silyl)methyl]triamide phosphoric acid or N,N′,N″-trimethyl-N,N′,N″-tris[(chlorodimethylsilyl)methyl]triamide phosphoric acid. NMR data show on the tetracoordinate state of silicon in these products. Professor Vadim Aleksandrovich Pestunovich, our chief, teacher and friend died on July 4^th, 2004     

Rotation barriers around N-C=bond in some cyclic α,β-enaminoketones and α,β-enaminothioketones

Conclusions Employing the method of complete analysis of the line shapes, we determined the activation parameters of the hindered rotation around the N-C=bond in 3-N, N-dimethylamino-5, 5-dimethyl-3-cyclohexene-1-thione, 3-N, N-dimethylamino-2-phenylindene-1-thione, and its oxygen analog. The values of the rotation barriers in the indene compounds are lower than in the cyclohexene derivatives, which can testify to a lower degree of p- conjugation between the unshared electron pair of the nitrogen atom and the electrons of the C=X (X=O, S) group in the indene ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2108–2110, September, 1975.