The chemical interpretation and the temperature dependence of the 14N nuclear quadrupole resonance of aniline and several derivatives

1968 ◽  
Vol 46 (22) ◽  
pp. 3595-3604 ◽  
Author(s):  
C. T. Yim ◽  
M. A. Whitehead ◽  
Donald H. Lo
Keyword(s):  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Coupling Constants ◽  
Temperature Range ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters ◽  
Phenylene Diamine

The 14N nuclear quadrupole resonance frequencies of aniline, o- and p-phenylene diamine, and p-chloro-, p-bromo-, and p-iodo-aniline were measured with a super-regenerative oscillator over a temperature range from 77 to 292 °K. The temperature dependence is analyzed. The chemical interpretation of the quadrupole coupling constants and asymmetry parameters is described.

NQR Studies of the Structure of Glasses and Crystalline Compounds

1992 ◽  
Vol 47 (1-2) ◽  
pp. 30-38 ◽  
Author(s):  
P. J. Bray ◽  
DongHoon Lee ◽  
De Gen Mao ◽  
G. L. Petersen ◽  
S. A. Feller ◽  
...  
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Borate Glasses ◽  
Low Frequencies ◽  
Structure Of Glasses ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole ◽  
Asymmetry Parameters

AbstractPure nuclear quadrupole resonance (NQR) spectroscopy at low frequencies (down to 275 kHz) has been used to investigate a number of borate, aluminate, and vanadate crystalline compounds and borate glasses. The values of the quadrupole coupling constants (Qcc) and asymmetry parameters (η) are obtained with error limits that are one or two orders of magnitude less than those for values obtained from NMR spectra. New sites, not resolved in NMR spectra, have been detected for boron in borate glasses.

On the Correlation of 35Cl Nuclear Quadrupole Coupling Constants with π→γ3 and π→γ5 Optical Electron Transfer Bands of Transition Metal Complexes and its Significance in Pi-Bonding

1969 ◽  
Vol 24 (2) ◽  
pp. 193-199 ◽  
Author(s):  
Paul Machmer
Keyword(s):  
Electron Transfer ◽  
Charge Transfer ◽  
Transition Metal ◽  
Metal Ions ◽  
Nuclear Quadrupole Resonance ◽  
Coupling Constants ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

From a consideration of odd-even intramolecular electron transfer processes in octahedrally co-ordinated transition metal complexes, two relationships have been derived. The first correlation describes π → γ3 optical electron transfer bands of the complexes K2OsCl6, K2IrCl6, K2PtCl6, K2PtCl4 as a function of the respective 35Cl nuclear quadrupole coupling constants. The second relationship correlates π → γ5 optical charge transfer transitions of the substances K2ReCl6, K2OsCl6, K2IrCl6 with the 35Cl nuclear quadrupole coupling constants of these compounds. By using this charge transfer model, a linear relationship has been verified between the optical electronegativity values of the quadrivalent transition metal ions W4⨁, Re4⊖, Os4⨁, Ir4⨁, Pt4⨁ and the 35Cl nuclear quadrupole coupling constants of their hexachloro complexes. The empirically established equation χMen+ = 0.537 which describes the 35Cl n.q.r. frequencies of the hexachloro complexes of Re4⨁, Os4⨁, Ir4⨁, Pt4⨁ and Pd4⨁ as a function of the optical electronegativity values χ of these metal ions, has been used to estimate 35Cl nuclear quadrupole resonance frequencies of chloro complexes as yet not probed by nuclear quadrupole resonance spectroscopy, e.g. Zeise's salt (KPtCl3C2H4), K3IrCl6, K2RuCl6, K3RhCl6 and K3MoCl6. Conversely, by the same procedure the optical electronegativity χ of W4⨁ and Au3⨁ has been estimated from the 35Cl quadrupole resonance frequency of K2WCl6 and KAuCl4 (χ W4⨁= 1.71 and χ Au3⨁=2.80). In the case of analogous bromo complexes, the equation χ Men+ = 0.19 mol accounts for the dependence of the 79Br nuclear quadrupole resonance frequencies upon the optical electronegativity of the metal ions. The assignment of electron transfer bands in other chloro complexes is discussed in the light of this “nuclear quadrupole resonance criterion“ of optical charge transfer bands.

scholarly journals 127I Pure Quadrupole Resonance Spectrum of Orthoperiodic acid, H5IO6

1971 ◽  
Vol 26 (11) ◽  
pp. 1813-1816 ◽  
Author(s):  
K. V. S. Rama Rao ◽  
Alarich Weiss
Keyword(s):  
Resonance Spectrum ◽  
Large Change ◽  
Coupling Constants ◽  
Temperature Range ◽  
Resonance Frequencies ◽  
Quadrupole Coupling ◽  
Quadrupole Resonance ◽  
Powder Samples ◽  
Small Change ◽  
Asymmetry Parameters

The NQR-spectrum of 127I in orthoperiodic acid, Η5ΙΟ6 , has been studied on powder samples in the temperature range 77 Κ ≦ Τ ≦ 398 Κ. The resonance frequencies ν1 of the transition m(±3/2) ⇄ m (±1/2) are 45.248±0.005 MHz (77 K) and 44.976 ± 0.005 MHz (296 K). For the⇄ transition m(±5/2) ⇄ m(±3/2) the resonance frequencies v2 are 83.478±0.005 MHz (77 K) and 83.960 ± 0.005 MHz (296 K). The corresponding quadrupole coupling constants, e2 q Q/h, are 282.977±0.005 MHz (296 K), and 281.892±0.005 MHz (77 K). The asymmetry parameters η have been determined as 0.2372±0.0001 (296 K), and 0.2580±0.0001 (77 K). A small change of 0.4% for e2 qQ/h is accompanied by a rather large change of 21% for η within the temperature range investigated. e2 q Q/h=f(T) shows a maximum at ~ 313 K. No evidence of phase transition has been observed by NQR spectroscopy between 77 K and 398 K.

An arsenic-75 nuclear quadrupole resonance study of α and β As4S3

1972 ◽  
Vol 25 (11) ◽  
pp. 2291 ◽  
Author(s):  
TJ Bastow ◽  
ID Campbell ◽  
HJ Whitfield
Keyword(s):  
Thermal Expansion ◽  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Electrostatic Field ◽  
Β Phase ◽  
Field Gradients ◽  
Α Phase ◽  
Resonance Frequencies ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

The nuclear quadrupole resonance frequencies of 75As in the α and β forms of As4S3 have been measured at 77, 195, and 293 K. The frequencies at 77 K were: α phase 64.87 65.94 79.56 MHz β phase 65.42 67.16 79.65 MHz An analysis is presented in terms of Townes-Dailey theory and of the temperature dependence in terms of Bayer-Brown theory. The differences in frequencies of the α and β forms were attributed to the effect of electrostatic field gradients, estimated by lattice sums. Allowance must be made for the thermal expansion of the lattice to obtain a consistent interpretation.

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