Vlado Tabacik

Infrared gas and matrix spectra of all eight symmetrical deutero pyrazole monomers

Abstract Infrared gas- and argon-matrix spectra of all eight symmetrical deuteropyrazole are reported. Assignments of all twenty-one fundamentals of these species are proposed, being in satisfactory agreement with product and sum rules. Based on these assignments a large set of sum and difference tones and harmonics is identified. A procedure for determination approximate average of an anharmonicity coefficient for high and low frequency modes is presented, which agrees satisfactorily with anharmonicity coefficients of particular fundamentals derived from first harmonic bands. Thermodynamic functions of pyrazole based on available spectroscopic data are given.

Spectres de vibration du trimethylsilanol

Abstract Vibrational spectra of trimethylsilanol -d0 and -d1 were measured by i.r. absorption (gas and pure liquid) and by Raman scattering (pure liquid). The assignment of bands to fundamental vibrations is baaed on the comparison with the spectra of analogous molecules, on the polarization measurements, the band envelope analysis, the Teller-Redlich rule, as well as the calculation a priori of fundamental frequencies and associated modes.

Vibrational spectra in cyclopropane series—IV. Analysis of the i.r. absorption and Raman scattering of cyclopropyl bromide

Abstract The Raman spectra of cyclopropyl bromide are measured in substantia and the i.r. spectra both in the gaseous and liquid states. The simultaneous analysis of the rotational envelope of the absorption bands and of the degree of depolarization of the Raman bands lead to the assignment of the 21 fundamentals. This assignment is corroborated by that of the binary combinations and by a normal coordinate treatment. The cyclopropyl bromide fundamentals can be deduced from those of cyclopropane, the observed differences being due essentially to the mass effect and only partly to the chemical character of the substituent. The thermodynamic functions are calculated in a usual harmonic oscillator and rigid rotator approximation.

Vibrational spectra in cyclopropane series: II. Symmetry and conformation in the gas phase of the monomer and dimer of cyclopropanecarboxylic acid

Abstract Infrared and Raman spectra of gaseous cyclopropanecarboxylic acid (C 3 H 5 COOH and C 3 H 5 COOD) were measured from 250 to 4000 cm −1 . The bands were assigned respectively to the monomer and to an associate. The depolarization ratio measurement, the vib—rot envelope study and the detailed analysis of the v (CO) and v (CH) regions enabled the symmetry and the conformation of the molecular entities in equilibrium to be determined. The monomer belongs to the C s symmetry group and the conformation of its predominant fraction is trans/trans . The associate is a centrosymmetrical dimer ( C i symmetry) having (trans/cis) 2 conformation. Some features of the geometry of the pseudocycle are discussed.

Coordonnées principales et moments principaux moléculaires calcul automatique de haute précision

Abstract The coordinates of N points (atoms) of a set (molecule) are given in terms of the lowest number (3 N -6) of independent and generally accessible geometrical parameters. This was achieved by using six (or nine) formulae and if necessary making some transformations. The simultaneous minimization of the number of parameters on the one hand and of the number of operations on the other is the main characteristic of the method described.

Vibrational spectra in cyclopropane series—III. Fundamental modes of cyclopropanecarboxylic acid monomer and of its -OD species

The i.r. and Raman spectra of cyclopropanecarboxylic acid CH2CH2CHCO2H and of its -OD species in the gas phase are obtained. The temperature shift of the equilibrium between rnonorner and dimer is used to identify the bands belonging to the monomer entity. The assignment of bands to the fundamental vibrations is based on the normal coordinate analysis, calculated correlation of fundamentals for the isotopically monosubstituted cyclopropanes, the use of the non-crossing rule, the application of Teller—Redlich product rule, the calculation of characteristics of vib—rot band envelopes and the measurement of depolarization ratios of Raman bands. The thermodynamic functions are calculated for the molecule considered as a rigid one in a usual harmonic oscillator approximation. The anharmonicity of the ν(OH) mode is also appreciated.

Vibrational spectra and normal coordinate analysis of two isotopomers of the thiosulfate ion

Abstract The Raman spectra of 18 O-thiosulfate ion (S 1 O −2 3 ) in H 1 18 O solution and the IR spectrum of 18 O-sodium thiosulfate in the solid have been obtained. Normal Coordinate calculations fitting all the fundamental wavenumbers of both 16 O and 18 O isotopomers have been carried out transferring the GVFF of the sulfate ion as the starting point and employing a symmetry force field for the least-squares adjustment procedure. A comparison of the results is made with the known force fields for several sulfur compounds.

Vibrations fondamentales des espèces d0, d2 et d6 totalement symétriques de l'acétaldazine anti—anti

Abstract The vibration spectra of three totally symmetrical isotopic species (- d 0 , - d 2 , - d 0 ) of acetaldazine CH 3 ·CH:N·N:CH·CH 3 are obtained both in liquid and gas states. The depolarization ratio ϱ p in liquid state and the vib—rot band envelopes in the absorption are measured for a majority of bands. An a priori calculation of fundamental vibrations, a calculation of different characteristics of the absorption band envelopes and a posteriori application of the product rule in the high and low frequency separation approximation led to identify in both (Raman and i.r.) spectra the majority of fundamental vibration bands. The calculation of binary combinations relating to the fundamentals enables to interprete the majority of bands of low intensity. The vibrational spectra are interpretable in conformity with the C 2 h symmetry and the anti—anti configuration of acetaldazine molecule.

Cuve pour la mesure des spectres d'absorption à l'état gazeux

Abstract A metallic cell is described for the measurement of the absorption spectra in the gas phase. This single pass cell is heatable up to 250°C and evacuable to 10 −6 torr. The sample, solid, liquid or gaseous at room temperature, can be introduced into the cell previously evacuated. The heating system provided a good stability of the temperature. It consists of three heatings, relating to the body, the windows and the sample-space of the cell, independently fed in a continuous and intermittent way. Results obtained with the cell for several years are reported.