Temperature dependence of the parameters of the equation of dispersion of electron-nuclear motions for the 121Sb NQR in RNO2·SbCl5 complexes

Семин, Г. К.; Кузнецов, С. И.; Burbelo, V. M.; Bryukhova, E. V.; Лотфуллин, Р. Ш.

doi:10.1016/0022-2860(94)08399-3

Cited by 19 publications

(4 citation statements)

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“…(1) into expression (13) and introduc ing an arbitrary origin along the q zz axis followed by per forming simple transformations leads to a simple differ ential equation with separated variables (η 0 -η) -1 dη = (q zz -q zz 0 ) -1 dq zz , (14) where η 0 = d(q xx -q yy )/dq zz = const´ and q zz0 = const″ for the given series of compounds. The solution of Eq.…”

Section: Resultsmentioning

confidence: 99%

“…The solution of Eq. (14) obtained after trivial transformations and multiplication of both parts by e 2 Q is as follows:…”

Section: Resultsmentioning

confidence: 99%

“…We assumed that the electronic configuration instability should affect this atom to the greatest extent. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17) at 77 K were measured on an ISSh 2 13 pulsed NQR spectrometer relaxometer designed and manufactured at the Special Design Bureau, Institute of Radio engineering and Electronics, USSR Academy of Sciences. They are listed in Table 1.…”

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Manifestation of electron-nuclear dynamics in 59Co NQR spectra of a series of cobaltocenium derivatives

2007

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A coupling equation relating the quadrupole coupling constant (e 2 Qq zz ) to the asymmetry parameter (η) of the electric field gradient for a series of cobaltocenium derivatives ( 59 Co NQR) is derived. The estimates of the correlation times of "slow" modulations of electron motions by tunneling processes lie in the range from 10 -12 to 10 -14 s. This corresponds to the interval of the characteristic times of nuclear motions.The formation of a chemical bond between a metal atom and cyclopentadienyl rings in metallocene com pounds has not been studied in detail so far. It is note worthy that conventional methods of investigation in cluding structural ones give no answer to the question about the role of dynamic effects in such systems. At the same time if there are two or more orbitally degener ate electronic levels having the same energy, the nuclear configuration can undergo a spontaneous distortion accompanied by considerable reduction of symmetry (Jahn-Teller effect 1 ). The distortion can be either static or dynamic. 2 Phenomena similar to the Jahn-Teller ef fect may also occur in electronically quasi degenerate systems where one nuclear core configuration corresponds to a number of very closely spaced (but not merged!) electron energy levels (Opic-Pryce effect 3 ), which can lead to the dipole instability that is impossible in the case of true Jahn-Teller effect. 1 The Opic-Pryce effect 3 cor responds to all intermediate situations from electronically degenerate systems to nondegenerate ones provided that the electron spin states remain unchanged. Thus, more than one configurational electron density distribution can exist in a molecular electron nuclear system. Electron tunneling assisted dynamic transitions between these con figurational states give rise to additional splitting of elec tron energy levels (so called tunneling or inversion split ting) and to subsequent onset of additional time depen dences of the electron distribution configurations. De pending on the ratio of the lifetimes of particular configu rational states and on the ratio of the times of complete electron tunneling and the characteristic times of nuclear motions, these differences either may or may not mani fest themselves as changes in the configuration of the mutual arrangement of atomic nuclei in the molecular system. Basic to the model presented in this work is analysis of the changes in the ratio of the characteristic times of nuclear motions and tunneling assisted "slow" modula tion of electron motions.Usually, the characteristic times of electron motions are assumed to be 5-10 orders of magnitude shorter than those of nuclear motions. This is the case of the well known Born-Oppenheimer approximation, 4 which ig nores the quantum coupling between electrons and atomic nuclei owing to large differences between the characteris tic times of corresponding motions (adiabatic approxi mation).However, typical electron tunneling probabilities (transparency coefficients) are of the order of 10 -5 -10 -10 , 5 which causes a significant incr...

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Section: Resultsmentioning

confidence: 99%

“…The solution of Eq. (14) obtained after trivial transformations and multiplication of both parts by e 2 Q is as follows:…”

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Manifestation of electron-nuclear dynamics in 59Co NQR spectra of a series of cobaltocenium derivatives

2007

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“…Narrow series I–XXXVI of various complexes taken from the literature are given in Tables . The interpreting of NQR spectra on occasion involves difficulties.…”

Section: Resultsmentioning

confidence: 99%

NQR parameters of complexes and polarizability effect

Egorochkin

Кузнецова

Хамалетдинова

et al. 2012

Magnetic Reson in Chemistry

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The literature data on substituent influence on the nuclear quadrupole resonance frequencies (ν), quadrupole coupling constants (e(2) Qq ⋅ h(- 1) ), and asymmetry parameters (η) for 36 series of the H-complexes, charge-transfer complexes, transition metal complexes and other donor-acceptor complexes have been considered, using the correlation analysis. Generally the ν, e(2) Qq ⋅ h(- 1) , and η values were first established to depend on the inductive, resonance, polarizability, and steric effects of substituents. The presence or otherwise of certain effects as well as relation between their contributions are determined by the type of series. The polarizability effect owes its existence to the appearance of an excess charge on the indicator centre as a result of the complexation. The contribution of this effect ranges up to 75%.

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NQRS Data for C7H7Cl5NO2Sb (Subst. No. 1000)

Chihara¹,

Nakamura²

2010

Landolt-Börnstein - Group III Condensed Matter

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Temperature dependence of the parameters of the equation of dispersion of electron-nuclear motions for the 121Sb NQR in RNO2·SbCl5 complexes

Cited by 19 publications

References 4 publications

Manifestation of electron-nuclear dynamics in 59Co NQR spectra of a series of cobaltocenium derivatives

Manifestation of electron-nuclear dynamics in 59Co NQR spectra of a series of cobaltocenium derivatives

NQR parameters of complexes and polarizability effect

NQRS Data for C7H7Cl5NO2Sb (Subst. No. 1000)

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