Lanthanum trilactate: Vibrational spectroscopic study − infrared/Raman spectroscopy

In this study lanthanum trilactate was prepared by neutralization reaction of lactic acid and lanthanum oxide, purified and identified by X-ray powder diffraction. Infrared spectra (Mid-IR region 4000–650 cm⁻¹) and Raman spectra (Stokes region 4000–100 cm⁻¹) of the high quality crystalline samples have been recorded and presented for the first time. For comparison DFT calculations were performed using Gaussian 09 D.01 and agreement between predicted and measured spectral data has been achieved. Acquired information can be utilized for substance identification for example in various industrial applications or in biological systems.     

Vibrational spectra of isocyanocyclopropane

Infra-red spectra of isocyanocyclopropane have been measured from 4000 to 400 cm⁻¹ in the vapour and to 200 cm⁻¹ in the liquid phase. The Raman spectrum of the liquid was obtained from 4000 to 50 cm⁻¹. A vibrational assignment of all fundamentals is proposed, which is in accord with those of structurally related molecules. Comparison with the vibrational spectra of cyanocyclopropane and cyclopropylacetylene shows the presence of a sizeable inductive effect of the nitrogen atom in isocyanocyclopropane.     

Vibrational spectra of cyanosubstituted cyclopropanes—III. Cyanocyclopropane and cyanocyclopropane-1-d1

The vibrational spectra of cyanocyclopropane have been reinvestigated with the gas phase i.r. spectrum reported for the first time. The i.r. spectra of cyanocyclopropane-1-d₁ have been measured from 4000 to 200 cm⁻¹ in the liquid and the gaseous phases and from 4000 to 400 cm⁻¹ in the polycrystalline state. Raman spectra of the liquid down to 50 cm⁻¹ were obtained. A vibrational assignment of all fundamentals is proposed. With the present data, we had to reassign several fundamentals published in the literature.     

Vibrational spectra and normal coordinate calculations for trimethylselenonium-d0 and -d9 ions and dimethyl selenide-d0, -d6

The i.r. (4000-30 cm⁻¹) and Raman (4000-0 cm⁻¹) spectra of trimethylselenonium iodide and dimethyl selenide have been obtained, together with those of their deuterated analogues. All the active fundamentals of the trimethylselenonium ion have been assigned, assuming C_3ν molecular symmetry. Normal coordinate calculations have been carried out for the trimethyl-selenonium ion and dimethyl selenide and the SeC force constants of both the compounds are compared, including those of other corresponding chalcogenides.     

Polarized Raman spectra,thermodynamic functions and bidders to internal rotation of 2,3-dimethoxy toluene

Polarized Raman spectra of 2,3-dimethoxy toluene have been recorded in the region 50–4000 cm⁻¹ and IR spectra in the region 200–4000 cm⁻¹. All the 63 (40a′ + 23a″) normal modes of vibration have been assigned assuming a C_s point group. Consistent assignments for the internal modes of vibration of methyl (CH₃) and methoxy (OCH₃) groups have been proposed. In addition thermodynamic functions have been computed over the temperature range 100–1500 K on a MIGHTY II computer and barriers to internal rotations for the three methyl (CH₃) tops and the two methoxy (OCH₃) tops about their respective axes have been determined, using the assigned torsional frequencies and assumed structural parameter for the 2,3-dimethoxy toluene. The barrier heights have been found to be greater than 2.5 kcal mol⁻¹ for all five tops.     

FT-Raman and infrared spectra,r0 structural parameters,ab initio calculations and vibrational assignment for nitryl chloride

The FT-Raman spectra (2000-30 cm⁻¹) of liquid and solid nitryl chloride, ClNO₂, along with the infrared spectra (2000-80 cm⁻¹) of the gas and solid have been recorded. All six fundamentals are confidently identified and the potential energy distributions determined from the force fields obtained from ab initio calculations. Several different basis sets have been utilized to determine the harmonic frequencies and force constants which are compared to the previously reported valence force constants. Structural parameters have been calculated with these basis sets including electron correlation with MP2, MP3 and MP4 perturbation. The calculated equilibrium structural parameters are compared to the experimental r₀ structural parameters. The spectra of the solid indicate that there are at least two molecules per primitive cell. All of these results are compared to the corresponding quantities for some similar molecules.     

Polarized infrared spectra of KHSeO4 single crystal

The polarized absorption i.r. spectra of KHSeO₄ single crystal were measured in the 4000-300 cm⁻¹ region at 300 and 25 K and discussed in relation to the crystal structure. The results obtained are compared with the spectra of the isomorphous KHSO₄ crystal.     

Internal modes of iodopentamethylbenzene in the disordered phase by vibrational spectroscopy

Infrared and Raman spectra of oriented and non-oriented single crystal of iodopentamethylbenzene were measured at room temperature over the 4000-400 cm⁻¹ region. The dichroism of the IR bands is discussed. An assignment of the fundamental vibrations of IPMB is presented and based on a comparison with the spectra of some similar molecules.     

Vibrational spectra and normal coordinate calculations for dimethyltelluride-d0, -d6 and dimethyltellurium difluoride-d0, -d6

The i.r. (4000-30 cm⁻¹) and Raman (4000-O cm⁻¹) spectra of dimethyltelluride, dimethyltellurium difluoride and their deuterated analogs have been obtained. All the active fundamentals of these compounds except methyl torsions were assigned, assuming a C_2υ molecular symmetry for both the tellurides. Normal coordinate calculations have been made in order to confirm the proposed assignments. The skeletal bond strength of the tellurides together with that of TeF₄ are discussed, using the valence stretching force constants.     

Diode laser spectroscopy of lithium chloride at elevated temperatures

Diode laser spectroscopy of lithium chloride in the gas phase (850°C) has been carried out in the region 621 to 693 cm⁻¹. Transitions of three isotopic combinations of lithium chloride (⁷Li³⁵Cl, ⁷Li³⁷Cl and ⁶Li³⁵Cl) have been measured with a nominal accuracy of ± 0.001 cm⁻¹. The results were combined with existing microwave data and fitted to the usual Dunham equation to produce accurate values of the pure vibrational parameters (Y₁₀, Y₂₀, etc.) and a number of high-order parameters.     

Infrared and Raman spectra of 2-(α-hydroxybenzyl)thiamine, 2-(α-hydroxycyclohexylmethyl)thiamine,their protonated forms and their complexes with zinc(II), cadmium(II) and mercury(II)

The infrared and Raman spectra of the ligands; 2-(α-hydroxybenzyl)thiaminium chloride (HBT), 2-(α-hydroxycyclohexylmethyl)thiaminium chloride (HCMT), and their protonated forms HBT·HCl and HCMT·HCl, as well as of their zwitterionic type complexes Zn(HBT)Cl₃, Cd(HBT)Cl₃, Hg(HBT)Cl₃ and Zn(HCMT)Cl₃, Cd(HCMT)Cl₃, Hg(HCMT)Cl₃, have been recorded in the region 4000-50 cm⁻. Several characteristic bands have been identified or tentatively assigned and are discussed in relation to the structures of the complexes. It is concluded from the spectra that the complexes are isostructural and that the bonding site of the ligands is the N(1′) atom of the pyrimidine moiety.     

Vibrational spectra of halogen substituted cyclopropanes—V. Trans-1,2-dichlorocyclopropane

The i.r. spectra of gaseous trans-1,2-dichlorocyclopropane were measured from 4000 to 400 cm⁻¹ and to 200 cm⁻¹ in the liquid phase. The Raman spectrum of the liquid was obtained from 4000 to 50 cm⁻¹. An assignment of all 21 normal vibrations was proposed on the basis of i.r. vapour phase band contours, Raman depolarization ratios, expected group frequencies and comparison with closely related molecules. There is excellent agreement with the normal modes previously assigned for the cis and trans isomers of the chloro, bromo and iodo analogues. The data indicate little interaction between the two CHCl moieties.     

Conformational equilibrium of dicyclopropyl ketone

The i.r. and Raman spectra of liquid dicyclopropyl ketone have been reinvestigated from 4000 to 200 cm⁻¹ with higher resolution than previously obtained. In addition, the i.r. spectrum of the polycrystalline solid was recorded from 4000 to 400 cm⁻¹. Contrary to published results, evidence has been obtained for a conformational equilibrium between the predominant cis—cis form and the gauche—gauche conformer.     

A vibrational spectroscopic study of 1-methyl and 2-methyl-5-aminotetrazole

The infrared spectra of 1-methyl and 2-methyl-5-aminotetrazole have been measured from 4000 to 180 cm⁻¹: polarized spectra have also been obtaine     

Infrared intensifies and frequencies of 2-butynenitrfie: Application to the atmosphere of Titan

The gas phase infrared spectrum of 2-butynenitrile (cyanopropyne), has been studied, in the 4000-50 cm⁻¹ wavenumber region. The most intense vibration bands have been located, their absolute intensities and the associated uncertainties have been estimated. These data, together with the recently reassessed absolute intensity of the v₆ band of propynenitrile, were then used to study the contribution of butynenitrile in the infrared spectra of Titan's atmosphere.     

Inelastic electron tunnelling spectra of 3- and 4-nitrobenzoic acids and nitrobenzene

Inelastic electron tunnelling spectra of 3- and 4-nitrobenzoic acids and nitrobenzene were measured in the range from 200 to 4000 cm⁻¹. The spectra were compared with that of benzoic acid. An approximate assignment of the spectral peaks was carried out by applying the assignments of benzoic acid and nitrobenzene based mainly on i.r. and Raman results. A broad band of the NH stretching mode (ca 3300 cm⁻¹) in the spectra of nitrobenzene and 3-nitrobenzoic acid implies a reaction between the adsorbent and hydroxyl groups on the surface of the alumina layer.     

Synthesis,spectroscopic and crystal field studies on some azido-chromium(III)-pyridine complexes

The new complexes mer-Cr(py)₃(N₃)₃, NaCr(py)₄(N₃)₄, KCr(py)₄(N₃)₄, and RbCr(py)₃(N₃)₄ (py = pyridine) have been prepared. Infrared (4000-50 cm⁻¹) and diffuse reflectance spectra (region 300-77 K) of powdered samples have been measured and discussed on bases of the known structures of these complexes. Single crystal absorption spectra for the mer-complex were obtained in the temperature range from 300 to 10 K revealing extensive vibronic structure associated with the ²E_g(O_h) and ²T_1g(O_h) electronic origins. Crystal field calculations were used to assign the bands in the vibronic region and to obtain estimates for the crystal field and Racah parameters for this class of substances. The parameters found for the mer-complex at 10 K are 10 Dq = 17906 cm⁻¹, B = 387 cm⁻¹ and C = 3381 cm⁻¹.     

Vibrational spectroscopic analysis of lithium hydrazinium sulfate

The low temperature polarized Raman spectra of lithium hydrazinium sulfate, LiN₂H₅SO₄, have been measured in the range 5–3500 cm⁻¹. The symmetry-based assignments for the observed modes are given. The room temperature polarized i.r. reflectivity spectra in the range 200–4000 cm⁻¹ were also measured to verify the presence of extensive TO—LO splitting in the sulfate ion ν₃ and ν₄ internal optic modes. In the lattice mode region, the lithium ion external optic modes are identified, and the spectra of the deuterated analog allow the identification of several modes due primarily to the external motions of either the sulfate or hydrazinium ions. Other lattice modes are found to be a mixture of sulfate and hydrazinium ion external motions. Coupling of the sulfate ion ν₃ modes and the hydrazinium ion group bending modes prevents an unambiguous assignment of the bands in the 1050–1200 cm⁻¹ spectral region. The N—H stretching region spectra contain a larger number of modes than predicted by a factor group analysis. These extra modes are discussed in terms of resonance interactions of the N—H stretching fundamental modes with overtones and combination modes.     

A reassignment of the vibrational fundamentals of sulfuryl chloride fluoride

Low temperature Raman spectroscopy has led to a significant revision in the assignment of the vibrational fundamentals of sulfuryl chloride fluoride (SO₂FCl). The fundamentals in cm⁻¹ are: (a′) 1230, 826, 632, 503, 422, 295; (a″) 1469, 476, 303. All are from gas-phase i.r. spectra except 295 cm⁻¹, which is from the liquid-phase Raman spectrum. The revised assignments are consistent with the predictions of Pfeiffer's normal coordinate calculations [Z. phys. chem., Leipzig 240, 380 (1969)].