Ultraviolet spectra and structure of unsaturated compounds of elements of group IV

Summary In the series of compounds CH₂=CH-(CH₂)_n-XR₃ the greatest bathochromic shift of the absorption bands is observed in the allyl compounds. The magnitude depends essentially on the nature of the atoms of the XR₃ group. The bathochromic shift is maximal for a nonplanar position of the double bond and the C-X bond. The results observed cannot be explained by d- interaction or inductive effect and they are in agreement with the idea of a - interaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12 p. 2203–2206, December, 1964     

Vacuum ultraviolet absorption spectra of vinyl compounds containing elements of group IV

Conclusions The substituants MR₃ in the compounds C=C-MR₃ and R₃M-C=C-MR₃ give rise to a bathochromic effect in the UV absorption spectra. The influence of the substituents does not agree with a mechanism of d- conjugation, and its explanation requires a consideration primarily of the - conjugation, and to a lesser degree of the inductive effect.     

Negative-ion mass spectra of heteroorganic compounds of group IV

Conclusions The dissociative resonance capture of electrons by the molecules of heteroorganic compounds of group IV was studied. It was shown that a new resonance state is observed with the introduction of a vinyl substituent. The nonadditive increase in the relative cross section for the formation of the negative ion with increase in the number of vinyl substituents is due to the stabilization of the molecule negative ion by * -* interaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 566–571, March, 1986.     

Photoluminescence spectra of clusters of group IV elements embedded in SiO2 matrices

Using a rf co-sputtering technique, SiO₂ films containing C, Si and Ge atoms were prepared and their Raman and photoluminescence spectra were measured. Raman spectra obtained are very broad indicating that the group IV elements are embedded in the form of clusters. The samples containing C clusters showed a very strong photoluminescence peak at around 2.1～2.2eV (visible with naked eye). The films containing Ge and Si clusters showed luminescence peaks at around 1.6～1.8eV. Strong luminescence was not observed for the samples containing well grown microcrystals a few nanometers in diameter.     

Solvent effects on infrared spectra of 2-acetylthiophene in organic solvents

Infrared spectroscopy studies of 2-acetylthiophene (ACTH) in 18 different organic solvents, both polar and non-polar, were undertaken to investigate the solvent-solute interactions. The frequencies of carbonyl stretching vibration upsilon(C=O) of ACTH were correlated with the properties such as the solvent acceptor number (AN) and the linear solvation energy relationships (LSER). The solvent-induced stretching vibration frequency shifts showed a better correlation with the LSER than the AN. A six-membered ring-like hydrogen bonding structure was presented and the solvent effects of ACTH in alcohol solvents were investigated in detail.     

Thermal analytical and infrared spectroscopic investigations on polymorphic organic compounds—IV

Twenty-four polymorphic compounds which show between two and four modifications are cited. The compounds described in detail are tetrabutylammonium iodide, tetraheptylammonium bromide, tetraoctylammonium bromide, 3-(3,4,5-trimethoxyphenyl)-2-propenoic acid andl-tyrosine ethyl ester hydrochloride. For the remaining nineteen compounds, only the number of modifications found, and their melting points where possible, are given.     

Photoelectron spectra of group V compounds. The elements: Sb4

The high-temperature He I photoelectron (PE) spectrum of gaseous Sb₄ is presented and assigned on the basis of the known PE ionisation energies of As₄ and P₄ and from SCC Xa eigenvalues and eigenvectors. Implications for the PE spectra of related antimony compounds are discussed.     

Raman spectra of the polymeric difluorides of the group IV elements and the structure of polydifluorosilylene

The Raman spectra for (SiF₂)_x and GeF₂ are reported. In the spectrum of (SiF₂)_x a band has been observed at 411 cm⁻¹ and is most probably associated with SiSi bonding in the compound; this is the first direct evidence for such a bond. The high degree of similarity between the spectra of (SiF₂)_x and (CF₂)_x suggests that (SiF₂)_x is a zig-zag helical chain polymer similar to (CF₂)_x.     

Nuclear magnetic resonance spectra of furan derivatives of IV B group elements (review)

Electronic and steric effects in furan derivatives were studied by the method of ¹H, ¹³C, ¹⁷O, and ²⁹Si NMR spectroscopy. The characteristic features of the influence of substituents on the screening and spin-spin interaction of ring nuclei in -substituted derivatives of furan in the presence of a second -substituent have been noted.Dedicated to Prof. A. R. Katritsky on his 65th birthday.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 879–890, July, 1993.     

Polar organic compounds with derivatized crystalline zirconium phosphates

Layered organic derivatives of crystalline zirconium phosphate were synthesized and investigated for their intercalation behaviours. Derivatized zirconium phosphates having hydroxy groups take up different polar molecules such as alcohols, amines etc. by increasing the interlayer distance determined by X-ray diffraction method. The intercalation processes on these materials can be considered as heterogenous phase acid-base reactions.     

Rapid access to infrared reference spectra of arbitrary organic compounds: scope and limitations of an approach to the simulation of infrared spectra by neural networks

Substance identification by infrared spectroscopy is performed by comparison of the experimental spectrum with a reference spectrum from a printed compilation or a database. If the analyzed compound can not be found in a database the corresponding reference spectrum has to be simulated. In order to achieve this, several reasonable candidates of structures for the compound at hand have to be conceived and for all these, infrared spectra have to be developed. The simulated spectrum that is most similar to the experimental suggests the correct structure. A rapid spectrum prediction method based on neural networks has been developed that supplies reference spectra for any organic compound. The scope and limitations of this method will be discussed on a test set of 16 compounds representing a broad range of organic chemistry.