Effect of Environmental Cations on Force Constants,Vibrational Mean Amplitudes and Bond Order of Metaloxygen Bonds in Some Octahedral Oxyanions

The general valenoe force field (GVFF), modified orbital valence force field (MOVFF), and modified Urey-Bradley force field (MUBFF) have been employed to calculate the force constants of octahedral Te⁶⁺o₆, and Ti⁴⁺o₆ anions in the presence of different environmental cations. The mean amplitudes and generalized mean square amplitudes of vibrations for these anions at temperatures; O°K,298. 16°K, and 500°K have also been calculated. Further, the metaloxygen bond order was estimated with the help of general valence stretching force constants. The effects of environmental cations on the force constants, mean amplitudes and π-bonding of metal-oxygen bonds have been critically discussed. The effect of atomic masses of anions on the ooriolis coupling constants of ‘f_iu species has also been outlined.     

Kinetic Constants Method for the Vibrational Analysis of Thallous Halide Dimers

The kinetic constants method is applied to the case of thallous halide dimers to evaluate the molecular constants such as, potential constants, compliance constants, mean amplitudes of vibration, coriolis coupling constants and centrifugal distortion constants, using the recent vibrational frequencies¹. The values of mean amplitude of vibration obtained by this method are in good agreement with the experimental values². The thermodynamic functions of thallous flouride for eleven temperatures ranging from 100K to 1000K are calculated on the basis of rigid-rotor, harmonic-oscillator approximation and are reported.     

Application of Mössbauer spectroscopy to the studies of FeCl3, SnCl4 and SbCl5 doped polypyrrole

Chemically polymerized polypyrrole was chemically doped with FeCl₃, SnCl₄, and SbCl₅. In⁵⁷Fe and¹¹⁹Sn ME studies, samples prepared under rigorously anhydrous conditions show only one type of iron and tin with Mössbauer parameters characteristic of FeCl ₄ ^– and SnCl₅ whereas in¹²¹Sb experiments two types of antimony corresponding to SbCl₃ and SbCl ₆ ^– have been detected.From the temperature dependence of the recoil free fraction the Mössbauer lattice temperatures were estimated as 125 K and 105 K for polypyrrole doped with iron chloride and with tin chloride respectively.     

Molecular Constants of MnF6 −2 Anion

Abstract

The normal coordinate analysis of XY₆ type of anions and molecules employing different force fields is well established.^1,2 Recently, the vibrational spectra and complete frequency assignment of MnF₆ ^?2 has been reported by Flint.³ Using the available vibrational data the force constants have been evaluated employing three potential models viz. general valence force field (GVFF), Urey-Bradley force field (UBFF) and orbital valence force field (OVFF). The mean amplitudes of vibration and Bastiansen-Morino shrinkages have also been computed at two temperatures.     

On Mössbauer effect in polypyrrole doped with selected metal halides

The reaction of partially oxidized polypyrrole [(C₄H₃N)₄⁺Cl₋]_n with FeCl₃ and SnCl₄ leads to the insertion of only one type metal halide species namely FeCl₄⁻ and SnCl₅⁻. The reaction with stannic halide is acid-base in nature whereas the reaction with ferric chloride may be either redox or acid-base. The use of SbCl₅ results in the insertion of two non-equivalent antimony halide species: SbCl₆⁻ and SbCl₃. Much simpler Mössbauer spectra can be obtained if in the doping reactions SbCl₅ or SbF₅ are replaced by NO₂⁺SbF₆⁻. Only one type of antimony with Mössbauer parameters characteristics of SbF₆⁻ is observed in this case. The Mössbauer lattice temperatures, θ_M, calculated from the temperature dependence of the recoil free fractions are 94 K and 105 K for FeCl₃ and SnCl₄ doped polypyrrole respectively. The obtained values are within the range typically observed for other conducting polymeric systems.     

Calculation of force constants and mean amplitudes of vibration of octahedral XY6 molecules using frequencies and zeta constants

Expressions involving vibrational frequencies, Coriolis coupling constants and masses of the atoms of the molecule that are invariant under symmetrical isotopic substitutions are derived for octahedral XY₆ molecules following the method given by Jagannathan and others. These invariants are used to calculate the force constants, compliance constants and mean amplitudes of vibration of 13 molecules of XY₆-type.     

Molecular constants of XeO3F2

The force constants of XeO₃F₂ have been evaluated using the general valence force field. The mean square amplitudes of vibration, the generalised mean square amplitudes and shrinkage constants, Coriolis coupling coefficients and centrifugal distortion constants have also been calculated for the first time using the vibrational frequencies and the structural parameters. The thermodynamic properties have been computed for the ideal gaseous state at 1 atmospheric pressure for 11 temperatures from 100° to 1000°K using a rigid rotor harmonic oscillator approximation.     

The GVFT Force Constants for PO4 3-/Td/

The force constants for the tetrahedral PO₄ ^3- ion have been calculated on the basis of the general valence force field with the application of the Wilson FG matrix method^1,2.     

The molecular structure and the analytical potential energy function of S2^- and S3^-

In this paper, the equilibrium geometry, harmonic frequency and dissociation energy of S2^- and S3^- have been calculated at QCISD/6-311＋＋G（3d2f） and B3P86/6-311＋＋G（3d2f） level. The S2^- ground state is of 2IIg, the S3^- ground state is of 2B1 and S3^- has a bent （C2v） structure with an angle of 115.65° The results are in good agreement with these reported in other literature. For S3^- ion, the vibration frequencies and the force constants have also been calculated. Base on the general principles of microscopic reversibility, the dissociation limits has been deduced. The Murrell-Sorbie potential energy function for S2^- has been derived according to the ab initio data through the least- squares fitting. The force constants and spectroscopic data for S2^- have been calculated, then compared with other theoretical data. The analytical potential energy function of S3^- have been obtained based on the many-body expansion theory. The structure and energy can correctly reappear on the potential surface.     

Normal co-ordinates through coriolis coupling constants

Normal co-ordinates, force fields and isotopic frequencies have been calculated for someXY ₃ andXY ₄-type molecules using coriolis coupling constants.     

Generalized Approach to Relaxed Force Constants

The main purpose of potential constants, i.e., force and compliance constants, is to provide a quantitative understanding of bonding relationships. Compliance constants have been shown to possess several mathematical advantages over conventional force constants.^1-3 Compliance constants, however, are parameters which decrease in magnitude as bond strength increases; consequently, their use as bond strength parameters is not particularly satisfying. The desirability of a measure of bond strength which increases in magnitude as the bond becomes stronger, and at the same time possesses all the advantages of compliance constants is self evident. For this reason, the relaxed force constant T_ii = 1/C_ii was introduced by a Jones some time ago.⁴ In the present communication, this approach is generalized to include relaxed interaction force constants. A brief discussion of their meaning is also presented.     

Generalized Approach to Relaxed Force Constants

The main purpose of potential constants, i. e., force and compliance constants, is to provide a quantitative understanding of bonding relationships. Compliance constants have been shown to possess several mathematical advantages over conventional force constants.^1-3 Compliance constants, however, are parameters which decrease in magnitude as bond strength increases; consequently, their use as bond strength parameters is not particularly satisfying. The desirability of a measure of bond strength which increases in magnitude as the bond becomes stronger, and at the same time possesses all the advantages of compliance constants is self evident. For this reason, the relaxed force constant T_ii=1/C_ii was introduced by Jones some time ago.⁴ In the present communication, this approach is generalized to include relaxed interaction force constants. A brief discussion of their meaning is also presented.     

Raman Study of InCl3

Abstract

The Raman spectra of a crystalline powder of InCl₃ and of a de-ionized water solution show the presence of four bands at 300.0, 289.2, 115.6 and 87.1 cm^?1, thus suggesting that InCl₃ is not a perfectly planar molecule.     

Measurement of Magnitude and Sign of Heteronuclear Coupling Constants in Transition Metal Complexes

Sets of specifically tailored E.COSY-type correlation experiments and double-quantum/zero-quantum (DQ/ZQ) experiments are presented which enable the determination of sign and size of small heteronuclear coupling constants across the metal center of transition metal complexes. For the octahedrally coordinated complexes, [Ru(TPM)(H)(CO)(PPh₃)]⁺[BF₄]⁻(1) and [Ir(TPM)(H)(CO)(CO₂CH₃)]⁺[BF₄]⁻(2), 14 of 15 and 15 of 15 possible two-bond scalar coupling constants across the metal center were measured, respectively, using¹⁵N and¹⁵N/¹³C enriched samples (TPM = tris(1-pyrazolyl)methane)). The reduced coupling constants²K_X-M-Y= 4π²²J/(hγ_Xγ_Y) were found to be positive when the coupled nuclei X and Y weretranswith respect to the metal center, and negative when the coupled nuclei were incisposition. The validity of this sign rule was verified forJ_CC,J_NN,J_PN,J_PC,J_CN,J_HP,J_HC, andJ_HNcouplings. Idiosyncracies associated with 2D NMR spectra for the sign determination of coupling constants with¹⁵N which lead to corrections for the signs ofJ_HN,J_PN, andJ_CNcouplings reported previously are discussed.     

Intermolecular Vibrational Coupling A Model Calculation for the Out-of-Plane Vibration of CO3 −- in Compounds with the Aragonite Structure

Abstract

¹³CO₃ ^?- substituted compounds with the aragonite structure show a fine structure of the out-of-plane vibration in the infrared spectra. A simple quantum mechanical model of coupled oscillators is developed to describe quantitatively the observed spectra. The spectra can be interpreted in terms of isolated ^12CO ₃ ^?- and ¹³CO₃ ^?- clusters, whose eigenfunctions interact. The heavy ions have localized vibrations, whereas clusters of the light ion with more than one ion show only localized vibrations at small coupling; stronger coupling results in resonant modes. Intensitytransfer from light to heavy ion bands is explained and the consequences of interaction between different clusters are discussed.     

The Pure Rotational Spectrum, Geometry, and Hyperfine Constants of Hafnium Monosulfide, HfS

The pure rotational spectra of seven isotopomers of hafnium monosulfide have been measured for several vibrational states. For the most abundant isotopomer, ¹⁸⁰Hf³²S, the J=1 - 0, J=2 - 1, and J=3 - 2 transitions were recorded up to the sixth vibrationally excited state. The constants Y₀₁, Y₀₂, Y₁₁, Y₂₁, and Y₃₁ were determined via a multi-isotopomer fit to a Dunham-type expression. In the process of fitting the data it was necessary to include Born-Oppenheimer breakdown correction terms. The equilibrium internuclear distance has been evaluated. For both the ¹⁷⁷Hf³²S and ¹⁷⁹Hf³²S isotopomers, nuclear hyperfine structure due to the hafnium nucleus was observed and notably large Hf nuclear quadrupole coupling constants, eQq, were determined.     

Acoustic mode vibrational anharmonicity of hexahelometallate crystals

The vibrational anharmonicity and Grüneisen parameters of hexahelometallate A₂MX₆ single crystals have been determined theoretically by making use of phonon lattice theory. The potential model employed to calculate these properties consists of long range coulomb, three body interactions, short range overlap repulsion effective upto the nearest neighbour ions and phonon-lattice interactions. These antifluorite structure compounds contain large MX²⁻₆- ions and as the interionic spacings are much greater than those of the alkaline-earth fluorite structure halides, their elastic constants are correspondingly smaller. The hydrostatic pressure derivatives of the second order elastic constants (SOEC) calculated for K₂SnCl₆, K₂ReCl₆, (NH₄)₂SnCl₆, (NH₄)₂TeCl₆, (NH₄)₂SnBr₆, and (NH₄)₂TeBr₆, are found to be positive and close to the experimental values. The vibrational anharmonicities of the long-wavelength modes are explained in terms of the acoustic mode Grüneisen parameters.     

Elastic constants,acoustic mode vibrational anharmonicity and Grüneisen parameters of hexahalometallate crystals

The room-temperature elastic constants of a number of hexahalometallate A₂MX₆ single crystals [K₂SnCl₆, K₂ReCl₆, (NH₄)₂SnCl₆, (NH₄)₂SnBr₆, (NH₄)₂SiF₆, Rb₂SnBr₆, K₂SeBr₆, (NH₄)₂TeBr₆, K₂PtBr₆ and (NH₄)2PtBr₆] have been measured either by Brillouin scattering or by the ultrasonic pulse echo overlap technique. Refractive indices have also been determined. These antifluorite structure compounds contain large MX^2?₆ ions and the interionic spacings are much greater than those of the alkaline-earth fluorite structure halides: their elastic stiffnesses are correspondingly smaller. Hydrostatic pressure derivatives of the elastic stiffness constants have been measured for K₂SnCl₆, (NH₄)₂SnBr₆ and (NH₄)₂SnCl₆ and are found to be positive; there is no marked softening of the long-wavelength acoustic-phonon modes at room temperature. The vibrational anharmonicities of these long-wavelength modes are discussed in terms of the acousticmode Grüneisen parameters, which are compared with the thermal Grüneisen parameters. For K₂SnCl₆ a mean of optic- and acoustic-mode Grüneisen parameters is shown to correlate well with the thermal Grüneisen parameter.     

Effect of variation of different nanofillers on structural,electrical, dielectric,and transport properties of blend polymer nanocomposites

In the present work, the effect of various nanofillers with different particle sizes and dielectric constants (BaTiO₃, CeO₂, Er₂O₃, or TiO₂) on blend solid polymer electrolyte comprising PEO and PVC complexed with bulky LiPF₆ has been explored. The XRD analysis confirms the polymer nanocomposite formation. FTIR provides evidence of interaction among the functional groups of the polymer with the ions and the nanofiller in terms of shifting and change of the peak profile. The highest ionic conductivity is ~?2.3?×?10^?5 S cm^?1 with a wide electrochemical stability window of ~?3.5 V for 10 wt% Er₂O₃. The real and imaginary parts of dielectric permittivity follow the identical trend of the decreasing value of dielectric permittivity and dielectric loss with increase in the frequency. The particle size and the dielectric constant show an abnormal trend with different nanofillers. The AC conductivity follows the universal Jonscher power law, and an effective mechanism has been proposed to understand the nanofiller interaction with cation coordinated polymer.     

LiC分子基态及其低电子激发态的多参考组态相互作用方法研究

采用包含Davidson修正的多参考组态相互作用(MRCI+Q)方法结合6-311++G(3df,3pd)基组计算了LiC分子基态(X4Σ-)以及五个低电子激发态(a2Π,b2Δ,c2Σ-,d2Σ+,A4Π)的势能曲线.将得到的势能曲线拟合到Murrell-Sorbie解析势能函数形式,确定了对应态的平衡结构Re、谐振频率ωe和离解能De等光谱数据,计算值与仅有的几个其他结果进行了比较.通过求解核运动的薛定谔方程首次报道了LiC分子几个低电子态在J=0下的振动能级、转动惯量和六个离心畸变常数(Dν,Hν,Lν,Mν,Nν和Oν).