scholarly journals 79/81Br nuclear quadrupole resonance spectroscopic characterization of halogen bonds in supramolecular assemblies

2018 ◽  
Vol 9 (20) ◽  
pp. 4555-4561 ◽  
Author(s):  
P. Cerreia Vioglio ◽  
P. M. J. Szell ◽  
M. R. Chierotti ◽  
R. Gobetto ◽  
D. L. Bryce
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Halogen Bond ◽  
Spectroscopic Characterization ◽  
Supramolecular Assemblies ◽  
Two Dimensional ◽  
Halogen Bonds ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

One- and two-dimensional bromine-79/81 NQR spectroscopy of halogen bond donors in a series of cocrystals shows changes in resonance frequency of up to 20 MHz and differentiates between crystallographically non-equivalent bromine sites.

scholarly journals Nuclear Quadrupole Resonance Frequency in Multilayered Cuprates

2009 ◽  
Vol 78 (12) ◽  
pp. 123704 ◽  
Author(s):  
Michiyasu Mori ◽  
Navid Afzal Shooshtary ◽  
Takami Tohyama ◽  
Sadamichi Maekawa
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Nuclear Quadrupole Resonance Frequency ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

Temperature and pressure variation of the 35Cl nuclear quadrupole resonance frequency in K2OsCl6

1970 ◽  
Vol 48 (20) ◽  
pp. 2411-2419 ◽  
Author(s):  
Robin L. Armstrong ◽  
Gregory L. Baker
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Coefficient Of Thermal Expansion ◽  
Pressure Variation ◽  
Temperature Phase ◽  
Thermodynamic Relation ◽  
Lattice Mode ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole

Measurements of the temperature and pressure dependence of the 35Cl nuclear quadrupole resonance (NQR) frequency in K2OsCl6 are reported. The resonance frequency is measured at atmospheric pressure for temperatures from 4.2 to 430 °K and for five temperatures between 284 and 410 °K for pressures to 5000 kg cm−2. A second-order phase transition occurs at about 45 °K. In the high temperature phase all of the chlorine atoms are crystallographically equivalent. The analysis carried out deals exclusively with the data obtained in this phase. A thermodynamic relation is used to relate the experimental quantities (∂v/∂T)P and (∂v/∂P)T to the theoretical quantity (∂v/∂T)V. The latter quantity is calculated for a particular model to describe the motional averaging of the electric field gradient at the chlorine sites. The model adopted includes two distinct mechanisms—the usual Bayer–Kushida averaging mechanism and a mechanism resulting from the partial destruction of π bonding by the lattice vibrations. The thermodynamic relation is used in conjunction with the combined data for K2PtCl6, K2IrCl6, and K2OsCl6 to evaluate the validity of the model proposed. It is concluded that the model provides a consistent explanation of both the temperature and pressure variation of the NQR data. In addition, the analysis provides information on the nature of the molecular orbitals of the [MCl6]2− complex ion, gives a rough estimate of the ratio of the coefficient of thermal expansion to the isothermal compressibility, and lastly, yields a value for the average frequency of the rotary lattice mode in the three substances.

Investigation of the Rotary Lattice Mode in R2PtCl6 Compounds. I. From Measurements of the 35Cl Nuclear Quadrupole Resonance Frequency

1971 ◽  
Vol 49 (19) ◽  
pp. 2381-2388 ◽  
Author(s):  
Douglas F. Cooke ◽  
Robin L. Armstrong
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Atmospheric Pressure ◽  
Nuclear Quadrupole Resonance Frequency ◽  
Published Data ◽  
Lattice Mode ◽  
Quadrupole Resonance ◽  
Temperature And Pressure ◽  
Nuclear Quadrupole ◽  
Static Lattice

Measurements of the temperature and pressure variation of the 35Cl nuclear quadrupole resonance (NQR) frequency in Rb2PtCl6 and Cs2PtCl6 are reported. The resonance frequency is measured at atmospheric pressure for temperatures from 4 to 500 K and at four temperatures between 290 and 380 K for pressures to 5000 kg cm−2. Previously published data for K2PtCl6 are also included in the analysis. Static lattice NQR frequencies are deduced. The differences between the static lattice frequencies are compared with the calculations of Smith and Stoessiger. Thermal averaging of the electric field gradient at a chlorine site is assumed to be dominated by the Q3, Q4, Q5, and Q6 internal modes of the PtCl6 octahedra and by the rotary lattice mode. The rotary mode frequencies are deduced; they are of similar magnitude and increase in the same sequence as the frequencies deduced from infrared and Raman data. An analysis of the pressure dependence of the NQR frequencies leads to pressure coefficients for the rotary mode frequencies. The influence of the cage of R atoms surrounding a PtCl6 octahedron is shown to increase through the series K2PtCl6, Rb2PtCl6, Cs2PtCl6. Finally, a thermodynamic analysis of the NQR data is presented which shows the importance of taking specific volume effects into account.

A nuclear quadrupole resonance investigation of the effect of pressure on molecular rotation in K2PtCl6

1969 ◽  
Vol 47 (10) ◽  
pp. 1095-1100 ◽  
Author(s):  
R. L. Armstrong ◽  
K. R. Jeffrey
Keyword(s):  
Resonance Frequency ◽  
Nuclear Quadrupole Resonance ◽  
Activation Volume ◽  
Classical Model ◽  
Nuclear Quadrupole Resonance Frequency ◽  
Molecular Rotation ◽  
A Value ◽  
Quadrupole Resonance ◽  
Quadrupolar Relaxation ◽  
Nuclear Quadrupole

The pressure dependences of the 35Cl quadrupolar relaxation rate and nuclear quadrupole resonance frequency in K2PtCl6 are measured for hydrostatic pressures up to 5000 kg cm−2 at six temperatures. The temperatures were selected so that the effects of pressure on the rotation of PtCl6 groups could be investigated. The relaxation resulting from the molecular rotation is discussed in terms of the simple classical model of an activated process. An activation volume ΔV* = 25.6 cm3 mole−1 for the rotation is deduced. The effect of the onset of the rotation on the nuclear quadrupole resonance frequency is noted. The results are shown to be consistent with earlier measurements on the 14N resonance in (CH2)6N4. The activation energy ΔE* for the rotation is shown to have a value between 12.6 and 18.8 kcal mole−1.

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