Quadrupole Coupling Constants and Mössbauer Isomeric Shifts in Antimony Compounds within Gaussian 98

2000 ◽  
Vol 55 (1-2) ◽  
pp. 276-280 ◽  
Author(s):  
O. Kh. Poleshchuk ◽  
J. N. Latosińska
Keyword(s):  
Experimental Data ◽  
Electron Density ◽  
Coupling Constants ◽  
Quadrupole Coupling ◽  
Extended Basis

The electron density and quadrupole coupling constants of molecules containing Sb are analysed. The NQCC for antimony, calculated using the extended basis 6-311G** are much lower than the experimental data, while the use of the small 3-21G* basis led to NQCC closer to the experimental ones.

The ab initio Calculation of Nuclear Quadrupole Coupling Constants with Special Reference to 33S

1992 ◽  
Vol 47 (1-2) ◽  
pp. 203-216 ◽  
Author(s):  
Michael H. Palmer
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Coupling Constants ◽  
Basis Set ◽  
Equilibrium Geometry ◽  
Relaxation Methods ◽  
Quadrupole Coupling ◽  
Nuclear Quadrupole ◽  
The Relationship

AbstractThe ab initio calculation of 33S nuclear quadrupole coupling constants (NQCC) for a range of S-containing compounds with S2, S4 and S6 bonding types is described. All of the calculations used a triple zeta valence + polarisation basis set (TZVP) of gaussian type orbitals; all of the molecules were studied at the TZVP equilibrium geometry. The electric field gradients (EFG) calculated were correlated with the experimental NQCC obtained by either microwave spectroscopy (MW), nuclear quadrupole resonance (NQR) or NMR relaxation methods; although the experimental data cover a wide diversity of chemical types over a long period of time, the slope of the relationship between the EFG (qii) and the NQCC (χii) yields a value for the 33S atomic quadrupole moment of - 0.064 barn, very close to recent calculations with a large atomic basis set, and to experimental data. The relationship between the EFG tensor components and the internal molecular structure features is discussed for a diverse series of molecules.

Die Polarisation der σ-Bindungen im Azulen

1972 ◽  
Vol 27 (1) ◽  
pp. 110-128 ◽  
Author(s):  
H. Seydewitz ◽  
E.D. Schmid
Keyword(s):  
Experimental Data ◽  
Ir Spectra ◽  
Linear Function ◽  
Electron Density ◽  
Coupling Constants ◽  
Ir Absorption ◽  
Absorption Intensity ◽  
Bond Lengths ◽  
Stretching Vibration ◽  
Stretching Vibrations

Abstract On the basis of a simple MO-approach a model to interprete the IR-absorption intensity of the aromatic CH-stretching vibration is developed. Accordingly the gradient of the CH-bond moment is a linear function of the ionicity of the CH-bond.Eight azulenes, which were deuterated at various specified positions, were synthetisized and out of their IR-spectra the gradients of the CH-bond moment at all positions of azulene could be determined. From these experimental data it is concluded, that in relation to benzene the electrons of the CH-bonds in azulene are displaced towards the C-atom at positions with high and towards the H-atom at positions with low π-electron density.Such a polarisation of the CH-bonds in azulene is confirmed, although only qualitatively, by the ionicities of the CH-bonds calculated by the CNDO/2-method and is also in accordance with other experimental observations such as bond lengths and angles, C13H-coupling constants, and the frequencies of the CH-stretching vibrations.It is demonstrated that experiment and calculation fail to correlate quantitatively due to in-adequacies inherent in the CNDO/2-method.

scholarly journals Analysis of the Quadrupole Coupling Constants and Mössbauer Iso- meric Shifts in Halogen Compounds Within the Gaussian98 Code

2000 ◽  
Vol 55 (1-2) ◽  
pp. 271-275
Author(s):  
O. Kh. Poleshchuk ◽  
J. N. Latosińska ◽  
B. Nogaj
Keyword(s):  
Experimental Data ◽  
Halogen Bond ◽  
Dipole Moments ◽  
Energy Levels ◽  
Point Of View ◽  
Coupling Constants ◽  
Good Test ◽  
Quadrupole Coupling ◽  
Bonding Properties

A comparison of the experimental and calculated nuclear quadrupole coupling constants of diatomic halogen, interhalogen, trihalide ions and complexes of pyridine is a good test of reliability of semiempirical and non-empirical theories as well as their usefulness in the interpretation of quadrupole coupling data from the qualitative and quantitative point of view. Therefore, a practical way of gaining insight into the bonding properties and electronic structure of such systems consists of combining semiempirical MO calculations with experimental data to derive reliable information. In the present work we report the results of ab initio studies of several iodine containing molecules and ions using the calculated NQCC as a test of the quality of the wavefunctions. To demonstrate the quality of our calculations, we compare the calculated halogen-halogen bond length and QCC with the corresponding experimental values for the compounds studied. With a few exceptions, the overall agreement with experiment is most satisfactory. The results on dipole moments and energy levels are also in a good agreement with the experimental data, however these quantities were measured only in the few cases.

Microwave Spectrum, Partial r0-Structure and 14N-Quadrupole Coupling Constants of 2-Cyanfurane

1976 ◽  
Vol 31 (6) ◽  
pp. 670-672 ◽  
Author(s):  
L. Engelbrecht ◽  
D. H. Sutter
Keyword(s):  
Nitrogen Atom ◽  
Electron Density ◽  
Cyano Group ◽  
Abundant Species ◽  
Microwave Spectrum ◽  
Coupling Constants ◽  
Frequency Range ◽  
Rotational Constants ◽  
Quadrupole Coupling

The microwave spectrum of 2-Cyanfurane was investigated in the frequency range between 11 and 39 GHz. The rotational constants of the most abundant species indicate that the Cyano-group is bent toward the ring oxygen at the central C-atom. From the measured quadrupole coupling constants one may conclude that π-electron density is pulled from the ring toward the Nitrogen atom

19F Nuclear Quadrupole Coupling in some Halomethanes

1986 ◽  
Vol 41 (1-2) ◽  
pp. 171-174 ◽  
Author(s):  
M. Frank ◽  
F. Gubitz ◽  
W. Ittner ◽  
W. Kreische ◽  
A. Labahn ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Simple Model ◽  
Temperature Dependence ◽  
Coupling Constants ◽  
Temperature Dependent ◽  
Distribution Method ◽  
Quadrupole Coupling ◽  
Time Differential ◽  
Nuclear Quadrupole

The 19F quadrupole coupling constants in CF4, CHF3, CClF3 and CHClF2 are reported. The measurements were carried out temperature dependent using the time differential perturbed angular distribution method (TDPAD). The temperature dependence can be satisfactorily described in the framework of the Bayer-Kushida theory. A simple model is used to explain the appearance of H-F and Cl-F coupling constants in CHF3/CHClF2 and CClF3, respectively.

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