NMR Spectra and structure of 1-vinylpyrazoles

Conclusions A¹H and¹³C NMR spectral analysis permitted evaluation of electronic and steric effects in 1-vinylpyrazoles. 5-Methyl-1-vinylpyrazoles have predominantly S-cis-N² orientation, while 1-vinylpyrazoles without substituents at C⁵ are conformer mixtures.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1012–1018, May, 1985.     

Spectra and structure of pyrylium salts

IR spectra of 20 specimens of 5, 6, 7, 8-tetrahydro-2-benzopyrylium 1, 3-disubstituted salts are obtained. The characteristic changes in the valence vibration bands for the pyrylium ring and for aromatic substituents are noted.     

Spectra and structure of salts of N-methylquinolones

The structures of salts of N-methylquinol-2- and -4-one are considered, using their IR spectra. It is shown that formation of salts from N-methylquinolones is accompanied by protonation of the carbonyl group. The problem of relating the 1500–1700 cm^–1 band in the IR spectrum of N-methylquinol-4-one is considered.     

Spectra and structure of silicon containing compounds

The Raman (50 to 3200 cm^–1) and infrared (50 to 3500 cm^–1) spectra of chlorodimethylmethoxysilane, Cl(CH₃)₂SiOCH₃, in the vapor and solid phases have been recorded. Raman spectra of the liquid including depolarization ratios have also been recorded. Optimized geometries and conformational stabilities have been obtained from ab initio calculations utilizing the RHF/3–21G* and RHF/6–31G* basis sets. The calculations from both of these basis sets indicated the gauche conformer to be significantly more stable than the trans conformer. Since the gauche has twice the multiplicity of the trans form it is unlikely that the trans conformer will be detected in the fluid phases at room temperature. This is supported by the fact that no infrared or Raman bands were found to vanish in the spectra of the crystalline solid. The vibrational frequencies have been calculated using appropriate scaling factors, and the vibrational spectra are interpreted in detail. The results have been compared with those obtained for some related molecules.Dedicated to Professor Dr. H. Kriegsmann on the occasion of his 70th birthdayFor part XX, see J Raman Spectrosc 26:in press (1995)Analytical R/D Department, Organic Products Division, Miles Inc., Bushy Park Plant. Charleston, SC 9411, USAChemistry Department, Mu'tah University, P.O.Box 7, Mu'tah-Karak, JordanDepartment of Chemistry, Moscow State University, Moscow, B-234, RussiaDepartment of Ceramic Engineering, Inha University, Nam-Ku, Incheon 160, KoreaDepartment of Chemistry, University of Oslo, P.O.Box 1033, 0315 Oslo, Norway     

Spectra and structure of sulfonium C-mononitro ylides

Conclusions Based on the data of the vibrational spectra and quantum-chemical calculation, in its electronic structure the nitro group in sulfonium C-nitro ylides is closer to the nitro groups in nonionized nitro compounds than in their salts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1403–1406, June, 1981.     

Spectra and structure of sulfonium C-dinitro ylides

Conclusions Based on the data of the vibrational spectra of sulfonium C-dinitro ylides and the quantum-chemical calculation of the electronic structure of the molecule the nitro groups of dinitro ylides in their electronic structure differ substantially from the nitro groups of both the gem-dinitroalkanes and their salts.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1407–1409, June, 1981.     

Spectra and structure of binary azeotropes V-acetone-cyclopentane

Acetone and cyclopentane make a minimum boiling homogeneous binary azeotrope with mole ratio 2:3. Some characteristic vibrational modes, as well as (1)H NMR signals change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on some vibrational modes involved and (1)H NMR signals show some changes on their position. In this work the FTIR and (1)H NMR spectra of pure acetone, pure cyclopentane and corresponding azeotrope were recorded, mutual influences resulting from azeotrope formation have been analyzed, and spectral changes has been discussed. The unit-structure of cluster have been deduced, based on mole ratio, boiling point depression of constituents, and comparison between the spectra obtained by FTIR and (1)H NMR techniques.     

Spectra and structure of binary azeotropes VI-benzene-methanol

Benzene and methanol make a minimum boiling point homogeneous binary azeotrope with the mole ratio 2:3. Some characteristic vibrational modes, as well as ¹H NMR signals change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on some vibrational modes involved, and ¹H NMR signals show some changes on their position. No IR, Raman, and NMR spectra have been reported for this constant boiling mixture, also there has not been any attempt to investigate the unit-structure of this azeotrope. In this work the FTIR, FT-Raman, and ¹H NMR spectra of pure benzene, pure methanol, and corresponding azeotrope were recorded, mutual influences resulting from azeotrope formation have been analyzed, and spectral changes has been discussed. The unit-structure of cluster has been deduced based on mole ratio, boiling point depression of constituents, and comparison among the spectra obtained by FTIR, FT-Raman, and ¹H NMR techniques.     

Spectra structure correlations in hydroxy and fluorapatite

The infra-red spectra of synthetic hydroxyapatite, Ca₁₀(PO₄)₆(OH)₂, and mineral fluorapatite, Ca₁₀(PO₄)₆F₂, over the range 4000-250 cm⁻¹ are reported. Comparison with the “free” phosphate ion indicates considerable perturbation of the PO₄³⁻ group in these solids; the observed absorptions suggest that in both compounds the phosphate symmetry is lowered to the extent predicted by a site symmetry analysis i.e. to C₁ in hydroxyapatite and C_s in fluorapatite, but the splitting of degenerate modes is not complete; this effect is more noticeable in fluorapatite. A weak interatomic crystal field arising out of the relatively low density of the atomic packing in these compounds is suggested as a cause of this incomplete removal of degeneracies. The spectroscopic evidence for the existence of hydrogen bonding of the OH … OPO₃ type in hydroxyapatite is discussed.     

Spectra and structure of mercury derivatives of primary nitramines

The mercury derivatives of primary nitramines were proved by molecular spectroscopy and quantum-chemical calculations to be covalent compounds. The mercury atom was found to be coordinated to the amine nitrogen atom.     

Spectra and structure of binary azeotropes II. Acetone-n-pentane

Acetone and n-pentane from an azeotrope with the mole ratio of 1:3, respectively. As the result of this azeotrope formation, some characteristic vibrational modes in FT-IR and chemical shifts in 1H NMR changes. The amount of these band and signal changes is an indication of the extend of interaction between two components and their orientation in unit structure of the cluster. FT-IR and 1H NMR spectra of pure substances and their azeotrope were recorded, spectral changes analyzed. Unit structure of azeotrope was deduced based on mole ratio, boiling point changes of pure components, and spectral changes in fundamental frequency and chemical shifts.     

Spectra and structure of binary azeotropes IV. Acetone-cyclohexane

Acetone and cyclohexane make a binary azeotrope with mole ratio 3:1. Some characteristic vibrational modes of acetone and cyclohexane change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on vibrational modes involved, and (1)H NMR signals show some changes on their position. FTIR and (1)H NMR spectra of pure substances and corresponding azeotrope were recorded, mutual influences resulting from azeotrope formation have been analyzed, spectral changes have been discussed. The unit-structure of cluster were deduced based on mole ratio, boiling point depression of constituents and comparison between spectra obtained by FTIR and (1)H NMR techniques.     

Spectra and structure of binary azeotropes I. Acetone-chloroform

Some characteristic vibrational modes of acetone and chloroform change due to the azeotrope formation. The extend of interaction of these molecules has significant effects on some vibrational modes involved, depending on unit structure in azeotrope cluster. Besides (1)H NMR signals undergo some chemical shifts, which show the effect of oncoming molecules on the target molecule. FT-IR and (1)H NMR spectra of pure substances and corresponding azeotrope were recorded, mutual influences due to azeotrope formation based on mole ratio, boiling point and spectral changes has been discussed. Unit structure of cluster deduced by investigating fundamental frequency shifts and (1)H NMR chemical shifts.