The vibrational spectrum of allene-d1

The i.r. spectra of allene-d₁ in the vapour phase and as a crystalline solid at 90 K were recorded in the region 5000-200 cm⁻¹. Raman spectra, including semi-quantitative polarization data, of the vapour and of the neat liquid, contained in a sealed tube at ambient temperature, were obtained. The fundamental frequencies were assigned in good agreement with results from earlier normal coordinate calculations.     

The vibrational spectrum of 1-bromo-1-chloroethylene

Vapor-phase and solution-phase i.r. spectra and liquid-phase Raman spectra were obtained for 1-bromo-1-chloroethylene. A complete vibrational assignment is made.     

The vibrational spectrum of anisole

The infrared and Raman spectra of C₆H₅OCD₃, C₆D₅OCH₃ and C₆D₅OCD₃ have been recorded in the liquid state. Vibrational assignments have been made and values for most of the fundamental vibrations have been obtained and correlated with those of C₆H₅OCH₃. Studies of the ultraviolet absorption spectrum have provided gas-phase data on a number of totally symmetric modes.     

The vibrational spectrum of tetrafluoropropyne

The i.r. spectrum of gaseous tetrafluoropropyne has been measured from 4000 to 100 cm⁻¹, and all of the observed bands have been assigned. The e mode frequencies of the CF₃ group are similar to those of other CF₃CCX species, and even though the a₁ modes are less regular, the variations can be explained without changes in force constants other than those involving the CX bond. Several bands, particularly ν₁ and combinations with ν₁, show pronounced sequence structure due to excited levels of ν₁₀, the CCC skeletal bend.     

The vibrational spectrum of dibutadieneiron carbonyl

A vibrational assignment has been proposed for (C₄H₆)₂Fe(CO). The internal butadiene modes show that there is very little interaction between the two C₄H₆ molecules, and that electronically it is very similar to C₄H₆ in (C₄H₆)Fe(CO)₃.     

The vibrational spectrum and structure of trifluorotrichlorodisiloxane

The vibrational spectrum of trifluorotrichlorodisiloxane (F₃SiOSiCl₃) is reported, analyzed and assigned in terms of a linear C_3v model, by comparison with that of structurally related hexachlorodisiloxane (Cl₃SiOSiCl₃). This is the first assignment of the vibrational spectrum for this molecule. The vibrational spectrum of Cl₃SiOSiCl₃ is assigned on the basis of a linear D_3d model, which is different from a bent C_2v model in the previous literature.     

A vibrational study of the infrared spectrum of dibromodifluoromethane,CBr2F2

The i.r. spectrum of natural dibromodifluoromethane has been recorded at medium resolution in liquid phase and at moderately high resolution in vapor phase. A number of regions have been analysed and the vibrational and vibrational—rotational features of the observed spectral structures interpreted. The frequency values pertaining to the fundamentals of the bromine isotopic species have been either directly measured or evaluated by “difference” bands and their isotopic splitting checked by a normal coordinates calculation. Absorptions due to the minor component ¹³CBr₂F₂ have also been observed and in part assigned.     

The vibrational spectrum and conformations of allyl chloride

Infrared and Raman spectra are reported for allyl chloride in vapour and liquid phases and also by matrix isolation in argon and nitrogen. Assignments are made in terms of a predominant low energy gauche form with a smaller amount of high energy cis form in all phases.     

The vibrational spectrum of methyltrioxorhenium(VII)

The inelastic neutron scattering and high-resolution FT-Raman spectra of methyltrioxorhenium are reported. Literature assignments of the modes below 1600 cm(-1) are largely confirmed with the exceptions of the methyl torsion and the ReO3 bending modes. The methyl torsion is observed for the first time at 200 cm(-1), while the band at 230 cm(-1) assigned previously to the torsion is shown to be a component of the factor group splitting of the solid. In the FT-Raman spectrum, the bands that derive from the E modes in the isolated molecule are split by the Cs site symmetry of the crystal. This allows an unambiguous assignment of these modes to be made. On this basis, the assignment of the ReO3 bending modes is reversed with the asymmetric mode at 325 cm(-1) and the symmetric mode at 276 cm(-1).     

The vibrational spectrum of 1,3-dithiole-2-thione

Infrared and Raman spectra of 1,3-dithiole-2-thione have been analysed partially through a normal coordinate calculation to give a vibrational assignment for the molecule.     

The vibrational spectrum of the normal and perdeuterated tetramethylammonium ion

Rather complete Raman and i.r. spectra of the two isotopic ions in aqueous solutions have been obtained and qualitatively interpreted.Some revisions of previous assignments are suggested, based on the new data and the isotopic frequency shifts. The presence of complex Fermi resonances was found in the CD stretching range.     

The vibrational spectrum and normal coordinate analysis of chlorodifluoromethane,CHClF2

The vibrational spectrum of chlorodifluoromethane has been reexamined. The i.r. and Raman spectra of the three isotopic species, ¹²CHClF₂, ¹³CHClF₂ and ¹²CDClF₂, have been obtained with better accuracy and higher resolution than in previous work. An SCF ab initio geometry optimization and quadratic force field calculation have been performed, and this force field has been further optimized to best fit the observed frequencies. The absorption spectrum of the ν₄, 2ν₆ region has been recorded at high resolution (0.002 cm⁻¹) and an analysis of the Fermi resonance perturbation has been carried out.     

Study of the vibrational spectrum of cuprorivaite

In this research, after tracing a history of the pigment, the preparation and analysis of samples of Egyptian blue have been reported. The main reactions taking place during its preparation are indicated. X-ray diffractions show that, starting from mixtures of precursors with stoichiometric composition, the product is practically only cuprorivaite. The kind of flux and cristallinity of silica does not seem determining factors for the pigment formation. Infrared and Raman spectra and an assignment of the bands are reported. Impurities ascertained are discussed on the basis on the data available.     

Reassignment of the vibrational spectrum of benzimidazole

New spectroscopic data on benzimidazole and benzimidazole-d2, using inelastic neutron scattering spectroscopy, has revealed previously unobserved bands. These new observations are incorporated into a complete assignment of the benzimidazole spectrum and shown to agree well with ab initio calculations on the system. The new assignment scheme eigenvectors have been correlated to those of indole.