Degenerate Deformation Research Articles

ON THE EFFECT OF THE TORSIONAL BARRIER IN TORSION-ROTATION-VIBRATION SPECTRA OF DIMETHYLACETYLENE-D3

Abstract Infrared specta of gaseous CH3C≡CCD3 were measured. With the aid of simulation spectra, torsional barrier in this molecule was evaluated to be 2±1 and 6±2 cm−1 from ν9 (CH3 degenerate stretching) and ν10 (CH3 degenerate deformation) perpenducular bands, respectively. The dependence of the barrier height on the vibrational state was found.

Molecular complexes of triphenylphosphine Oxide and triphenylarsine oxide with antimony(III) and bismuth(III) halides. Vibrational spectra and structures

Nine new complexes are prepared (SbBr 3·2(C 6H 5) 3PO, Sbl 3·2(C 6H 5) 3PO, BiCl 3·3(C 6H 5) 3PO, SbBr 3·2(C 6H 5) 3AsO, [SbBr 2·4(C 6H 5) 3AsO] Br, [SbI 2·3(C 6H 5)3AsO]I, BiCl 3·2(C 6H 5) 3AsO, BiBr 3· 3(C 6H 5) 3AsO and 2BiI 3·3(C 6H 5) 3AsO) and their molecular structure and the structure of the complexes SbCl 3·2(C 6H 5) 3PO, BiBr 3·2(C 6H 6)3PO, BiI 3· 2(C 6H 5) 3PO and SbCl 3·2(C 6H 5) 3AsO discussed on the basis of vibrational spectra. It is shown that the mean shifts of ν(PO) and ν(AsO) are proportional to the Lewis acidity and basicity of the components. taking into account the configuration and the number of ligands. The structure of the bridging halogen bonds is discussed and caution is suggested in deducing the stereochemical inactivity of the electron lone pair of antimony(III) and bismuth(III) in polynucluear complexes from crystal structure data only. the degenerate deformation vibrational of the PO and asO bonds in the far infrared spectra of the free oxo-bases are located and the 1050–1150 cm −1 region in triphenylphosphine oxide in reassigned.

Electronic states of C2H6+

The complete photoelectron spectrum of ethane has been measured in the valence region using Ne, He I, and He II resonance radiation. The resolution of these spectra is sufficient to partially resolve vibronic structure accompanying the transition to the ground ionic state. The similarity of this structure with that obtained from model calculations using the Jahn-Teller theorem strongly suggests that the active vibration in this transition is a doubly degenerate CH3 deformation mode and that the ground ionic state is a Jahn-Teller split 2 E g state. These experiments suggest a 2 A 1g term for the first excited ionic state. The transition to the 2 A 2u state of the ion contains evidence for two active vibrations v 1 (C–H stretch) and v 3 (C-C stretch).

The infrared spectrum of single crystals of nitrogen-deuterated l-alanine

The polarized infrared spectrum of nitrogen deuterated l-alanine single crystals is reported. The dichroism of the bands between 3200 and 300 cm −1 is analyzed correlated with local symmetry models for groups of atoms in the molecule. Analysis of the models were found to yield assignments consistent with those previously reported for alanine. Reassignment of the symmetric degenerate deformation modes of the NH 3 +group axe suggested by the observed dichroism of the deuterated alanine spectrum. Assignments newly resolved polarization behavior of the methyl hydrogen stretching bands are reported. Splitting of the methyl and ammonium group degenerate modes are observed along with factor group splittings of up to ∼ 12 cm −1 in a few of the fundamental bands. The value of considering the CH 3 and NH 3 + groups as identical dynamical units in the analysis of the skeletal modes of normal alanine is emphasized in the present study.

Organische Metallkomplexe—V. I.R.-Spektren von 13C-, 18O- und 2H-markierten Acetylacetonaten

Zusammenfassung Infrared spectra of 13 C-, 18 O- and 2 H-labeled acetylacetonates provide a basis for the unambiguous assignment of vibrational frequencies. The assignments are supported by the spectra of orientated molecules in polarized light. In contrast with previous work, the frequencies of the Cu(II) complex in the range between 1600 and 1250 cm −1 are assigned as follows: 1578 cm −1 mainly CO stretching ( B 1 u ), 1527 cm −1 mainly CCC stretching ( B 2 u ), 1430 cm −1 CH 3 degenerate deformation, 1397 cm −1 CO stretching B 2 u ), 1354 cm −1 CH 3 symmetric deformation, 1281 cm −1 CCC stretching ( B 1 u ).

Infrared Spectrum of Germylacetylene

Infrared grating spectra of gaseous GeH3CCH and GeD3CCH were obtained over the 4000-to−140-cm−1 region, and the fundamentals of both molecules were completely assigned using a C3v symmetry model. Q-branch structure was resolved for three of the five perpendicular bands of GeH3CCH, and values for all five Coriolis coupling constants were obtained from analysis or from the zeta sum rule. Anomalous band structure was observed for the C≡C stretching mode, similar to that reported for other monosubstituted acetylenes. A strong rotational perturbation was also observed in the degenerate GeH3 deformation mode which was interpreted as arising from a second-order Coriolis interaction.

Some characteristic frequencies of amino acids

Abstract On the basis of the observations of the infrared absorption spectra of several α-amino acids, some of the related compounds, some of their N- and C- deuterated derivatives, their 15N-substitution products, their sodium salts and their hydrochlorides, the characteristic frequencies are indicated of their following vibrations: NH3+ degenerate deformation, NH3+ symmetric deformation, ND3+ deformations, NH3+ rocking, ND3+ rocking, C-N stretching, COO− antisymmetric stretching, COO− symmetric stretching, some COOH vibrations and some COOD vibrations. Brief discussions are given of the natures of actually observed bands corresponding to these vibrations.