Vibrational Spectra of 4-Benzoylpiridine and the 18O Substituted Derivative

Abstract

Infrared and Raman spectra of 4-benzoylpiridine (4BP) and its ¹⁸O substituted derivative have been recorded in the solid and in the molten state. Polarized Raman spectra in the molten state have also been measured. The assignment of the vibrational bands is performed on the basis of isotopic shifts, group vibrational concept and polarization features of the normal modes. The previous assignment of the in- and out-of-plane deformations of the carbonyl group and the fundamentals below 700 cm^?1 are questioned and corrected.     

Infrared Study of Anthraquinone-Anion-Radical and its 180 Labelled Isomer

Abstract

Infrared spectra of anthraquinone and anthraquinone-¹⁸0-anion-radicals have been investigated. Anion-radicals have been obtained by electrochemical reduction of anthraquinone and anthraquinone-¹⁸0 in dimethylsulf-oxide-d₆.

Band assignment has been performed using the group vibrational concept and isotopic shift data. The assignment of IR active C[dbnd]O stretching band and the other bands in 1150–1800 cm^?1 region of anthraquinone anion-radical (anthrasemiquinone) have been discussed and compared with those of some other ¹⁸0 labelled anion-radicals. A decrease of 182 cm^?1 has been found forafter transformation of the neutral quinone into anion-radical.     

Vibrational Assignment of N-Phenylphthalimide and 15N-Phenylphthalimide

Abstract

The i.r. spectra of N-phenylphthalimide and ¹⁵N-phenylphthalimide have been measured in 4000–100 cm^?1 frequency range as KBr and polyethylene pellets and as chloroform solutions. The Raman spectra (4000–50) cm^?1 of microcrystalline powder of the of the same compounds have also been investigated.

A detailed assignment of most of the observed frequencies has been proposed on the basis of the group vibrational concept, isotopic shift data and analogies with the spectra of related molecules. Some literature data have been discussed and some frequencies are reassigned.     

The Vibrational Spectra of 9-Fluorenone and Some of Its Isotopic Isomers

Abstract

Vibrational spectra of 9-Fluorenone, 9-Fluorenone-¹⁸O and 9-Fluorenone-d₈ have been recorded in the solid state and solutions in the infrared and (4000–100 cm^?1) and in the Raman (4000–50 cm^?1). Differential infrared linear dichroic spectra have also been measured. The assignment of the vibrational bands is performed using the group vibrational concept, isotopic shifts and polarization features of the normal modes.     

Vibrational Spectra of 2,2′-Pyridil and 2,2′-Pyridil-18O and Assignment of Infrared and Raman Bands

Abstract

Vibrational spectra of 2,2′-pyridil and 2,2′-pyridil-¹⁸O in the solid state and in solutions have been measured in the Raman (4000–50 cm^?1) and infrared (4000–100 cm^?1). The assignment of the bands observed is performed using the group vibrational concept and isotopic shifts data of the normal modes. The presence of synand anti-phase vibrations of both pyridyl rings is discussed. The results are compared to the corresponding data for some similar molecules.     

The Vibrational Spectra of a Series of Simple Phosphorus/Chromium Polyoxoanions

The infrared and Raman spectra of polycrystalline samples of K₂HPCr₂O₁₀, Na₃PCr₃O₁₃.3H₂0, K₃PCr₄O₁₆ and (NH₄)₃PCr₄O₁₆ were recorded and discussed. A general vibrational assignment for the internal vibrations of these species is proposed.

The structural characteristics of an interesting series of simple polyoxoanions of the PCr_nO^3- _3n+4 type have been determined recently^1–7. These species are essentially built from a central PO₄ -tetrahedron which share a different number of corners with CrO₄ -tetrahedra.

As part of our present studies on different physico-chemical properties of polyoxoanions, we have investigated the vibrational spectra of crystalline species containing the following anions: HPCr₂O^2- ₁₀, PCr₃O^3- ₁₃ and PCr₄O^3- ₁₆.

As the three species have some common structural features, their vibrational spectra can be analyzed and compared in terms of these common building elements, i. e., terminal CrO₃ and PO groups and POCr bridges.

The interatomic distances in the above mentioned units are also very similar in all the anions and the Cr-O distances are similar to those found in the normal (triclinic) form of K₂Cr₂O₇ ⁸.     

Infrared Spectra of the Anion-Radicals of Benzophenone and Some of Its Isotopic Isomers

Abstract

Band assignment of the infrared spectra of the anion-radicals of benzophenone-d_O, -d₁₀ and ¹⁸O has been given on the basis of isotopic shifts. The frequency of the ν_C=O band decreases by ca. 270 cm^?1 with the transformation of neutral keton into anion-radical, due to the strong electron-withdrawing character of the carbonyl group; frequencies of the other modes decrease slightly, down to 30 cm^?1.     

Vibrational spectra of Na4P2O7·10H2O

The IR and Raman spectra are measured and analysed for sodium pyrophosphate decahydrate. The spectra are interpreted on the basis of P₂O ₇ ⁴⁻ ion and water vibrations. The observed results fit with the features predicted for the factor goup model. The appearance of two sets of frequencies in the stretching and bending regions of water suggests the existence of two kinds of water molecules in the crystal. This is confirmed by deuterium substitution.     

Infrared Spectra and Configuration of Anion Radical and Dianion of Benzil and Benzil-18o

Abstract

Infrared spectra of the products of one- and two -step reduction of both benzil and benzil-¹⁸0 have been investigated in dimethylsulfoxide-d₆ and tetrahydrofurane solutions. Anion-radicals have been obtained by electrochemical reduction of benzil and benzil-¹⁸0; dinegative ions have been prepared by reduction of the same ketones with potassium mirror in vacuo. The band assignment has been performed using the group vibrational concept and isotopic shift data. The previous assignment of the C[dbnd]O stretching band of benzil anion-radical-has been discussed and corrected. Two bands in the infrared spectra of benzil dianion have been found to be sensitive upon ¹⁸0 isotope labelling. This result certifies the presence of cis-configuration of benzil dianion in the investigated solutions. A decrease of ca. 290 cm-¹ has been found for vC[dbnd]O after the transformation of the neutral benzil into an anion-radical. Conversion of benzil anion-radical into dianion has been accompanied by an additional vC[dbnd]O downward shift of 105 cm^?1     

Vibrational Spectra of Thiazole-2-Carboxylic Acid and Thiazole-2-Carboxylate Ion

The i-r. spectra of thiazole-2-carboxylic acid and thiazole-2-carboxylate ion as CsI pellets and Nujol mull as well as Raman spectrum of an aqueous solution of the salt have been investigated. Most vibrations have been assigned on the basis of group frequencies and by correlation between the spectra of both molecules. The -COOH characteristic vibrations have been assigned as vibrations of the intermolecularly associated species.     

Vibrational Spectroscopic Analysis of L,D-Dipeptides

Raman and infrared spectra of Boc-D-Leu-L-Leu-OMe, Boc-L-Ile-D-aIle-OMe and its N-deuterated derivative have been obtained. Normal mode frequencies on the models of these dipeptides have been calculated and the conformationally sensitive amide I, II, III and V modes are compared with the experimentally observed frequencies. The calculated frequencies are in good agreement with the observed frequencies. It is observed that the amide frequencies in these dipeptides are not very sensitive to their backbone conformation. This is in contrast to the well established conformational dependence of the amide modes in peptides, polypeptides and proteins. The normal mode calculations on these peptides also show absence of mixing in amide I and II modes, and hence lack of appreciable splitting in these modes due to transition dipole coupling.

     

Vibrational spectra of (NH4)3ZnCl5

IR and Raman spectra of (NH₄)₃ZnCl₅ have been recorded. The observed spectra have been analysed on the basis of the vibrations of ZnCl ₄ ²⁻ and NH ₄ ⁺ ions. The appearance of multiple Raman bands indicates the presence of two different types of ammonium ions. The effect of anisotropic crystalline field over the ZnCl₄ and NH₄ tetrahedra is also discussed. The assignment of internal modes has been verified by the potential energy distribution calculations.     

三硼酸铯和硼酸铯锂晶体的晶格振动光谱研究

本文对新型非线性光学晶体三硼酸铯（ＣｓＢ３Ｏ５∶ＣＢＯ）和硼酸铯锂（ＣｓＬｉＢ６Ｏ１０∶ＣＬＢＯ）进行了晶格振动光谱研究。首先对两种晶体的基本晶格振动模进行了对称性分类,记录了两种晶体低温下的拉曼光谱和室温下的红外反射光谱,对晶体的晶格振动模进行了认定,将振动模归属于平面六元环（Ｂ３Ｏ６）和四面体（ＢＯ４）。然后比较了ＣＢＯ,ＣＬＢＯ和ＬＢＯ（ＬｉＢ３Ｏ５）三种晶体的晶格振动光谱,讨论了阳离子对振动光谱的影响。另外,还讨论了硼酸盐晶体晶格振动模ＬＯ ＴＯ分裂的大小与晶体非线性光学系数之间的关系。     

Rotational analysis of the 0–9, 0–10 and 0–11 bands of theA 2II u -X 2II g band system of (16O18O)+

High-resolution spectra of the 0–9, 0–10 and 0–11 bands of theA ²II _u —X ²II _g system of (¹⁶O¹⁸O)⁺ ion have been studied for their rotational structure. This study enables a direct determination of the Λ-doubling parameters of theA ²II _u andX ²II _g states. The model of ‘pure precession’ explains, though not entirely, the Λ-doubling of theX ²II _a state as arising out of its interaction with theB ² Σ _g ⁻ state. The Λ-doubling in theA ²II _u state was found insignificant.     

Raman and Infrared Spectra of Cd(15NH3)2Cl2 and Local Symmetry Force Field

The infrared and Raman spectra of Cd(¹⁵NH₃)₂Cl₂ are reported and a comparison is made between the normal and ²H isotope substituted compounds. A further refinement of the Local Symmetry Force Constants was carried out.     

Vibrational Spectra of Arsenates and Phosphates of the Type Kcaln(XO4)2

The infrared and Raman spectra of polycrystal-line samples of different compounds of the types KCaLn(AsO₄)₂ and KCaLn(PO₄)₂, belonging to the hexagonal LaPO₄, structural modification, were recorded and discussed. A complete vibrational assignment, based on a factor group analysis, is proposed. The influence of the different lanthanide cations on the internal vibrations of the XO₄ groups is briefly discussed and some comparisons with related compounds are also made.

It is well known that simple lanthanide arsenates, phosphates, vanadates and cnromates (V) of the type LnXO₄ belong to two different structural types.     

Vibrational Spectra of Cd(NH3)2Br2 with 2H Isotopic Substitution and Local Symmetry Force Field

The infrared and Raman spectra of the cadmiumdiammindibromide with ²H - isotopic substitution, have been measured. In order to examine the transferabilities of the skeletal and -NH₃, ligand force constants, a normal coordinate analysis was carried out based on a Local Symmetry Force Field (LSFF). The results support the experimental assignments.     

Line positions and energy levels of the O substitutions from the HDO/D2O spectra between 5600 and 8800 cm

Absorption spectra of HDO/D₂O mixtures recorded in the 5600-8800 cm⁻¹ region with a total pressure of water from 13 up to 18 hPa and an absorption path length of 600 m have been analyzed in order to obtain new spectroscopic data for HD¹⁸O and D₂¹⁸O. In spite of the low natural ¹⁸O concentration (about 2×10⁻³ with respect to the ¹⁶O one), about 1100 transitions belonging to HD¹⁸O and more than 280 transitions belonging to D₂¹⁸O have been assigned. Most of the D₂¹⁸O transitions belong to the ν₁+ν₂+ν₃ and 2ν₁+ν₃ bands. Sets of energy levels for seven vibrational states of D₂¹⁸O and four states of HD¹⁸O are reported for the first time. The comparison of the experimental data with the calculated values based on Partridge-Schwenke global variational calculations is discussed.     

烧绿石型富氧相Ce_2Zr_2O_8与缺氧相Nd_2Zr_2O_7的振动光谱及XPS对比研究

采用石墨还原法成功制备了富氧相Ce2Zr2O8,选用缺氧相Nd2Zr2O7替代其前驱体CeZrO3.5+δ进行结构对比分析,利用X射线衍射(XRD)、拉曼光谱(Raman)、红外光谱(IR)及X射线光电子能谱(XPS)对样品体、表晶体结构进行表征。XRD结果表明,Ce2Zr2O8相具有典型烧绿石结构特征,表征Ce/Zr阳离子有序排列的超结构峰非常明显,但其Zr—O配位体由前驱体中的[ZrO6]八面体转变为[ZrO8]立方体,[ZrO8]配位体形成大大降低了Ce2Zr2O8的结构稳定性。Raman和IR结果表明,Ce2Zr2O8相的振动光谱谱带比其前驱体替代物Nd2Zr2O7显著增多,说明氧离子的富集导致Ce2Zr2O8相中某些振动简并峰消除简并,该结果进一步证实了其结构对称性较前驱体更低。XPS结果表明,Ce2Zr2O8相表面Ce(Ⅳ)特征峰(916.3eV)非常明显,没有Ce(Ⅲ)特征峰(885eV)出现,说明该相前驱体中的Ce3+已被完全氧化成Ce4+;Ce2Zr2O8相中Zr(3d)结合能与萤石相Gd1.2U0.8Zr2O7+y接近证实其表面形成了与体相一致的[ZrO8]配体;O(1s)低位结合能升高表明Ce2Zr2O8体相氧种介于晶格氧和吸附氧之间,高位氧峰出现说明其表面含有吸附氧,吸附氧与Ce2Zr2O8体相结合强度介于CeO2和Nd2Zr2O7之间。     

Hydrogen Bonding Effects on Electron Population and 13C Chemical Shift of Base: Alcohol Pyridine Complexes

The carbon chemical shifts of pyridine associated to various aliphatic and aromatic alcohols are measured. Actual effects of hydrogen bonding formation on 13c shifts, have been characterized by evaluating in first, anisotropy and non specific medium effects. Linear relationships are obtained between 13C shifts and the IR frequency shifts. Positive slopes are observed for C-β and C-γ in agreement with the electron population change, but a reverse slope results for C-α carbon.