Local Electric Field Gradients in Anionic and Cationic Positions of Cesium Perchlorate

Abstract

Polycrystalline CsC10, is studied over the range from 95 to 440 K by 35Cl and 133Cs NMR in the field B, = 7.04 T. From the analysis of the lineshape the quadrupole coupling constant C, and the asymmetry parameter .r? at the nuclei 35Cl and 133Cs are determined. The temperature dependence of C, is linear for both the nuclei with a negative temperature coefficient. A sharp break of ~( '~~c s ) at 342 K is due to the change in the relative values of the tensor components qij of the electric field gradient on 133Cs. The temperature dependence of qij is considered in relation to the anisotropy of the thermal expansion and a numerical evaluation of the thermal expansion coefficient is made.Im Temperaturbereich von 95 bis 440 K wird mittels 35Cl-und '33Cs-NMR in einem Feld B, = 7.04 T polykristallines CsClO, untersucht. Aus der Analyse der Linienform werden die Quadrupolkopplungskonstante C , und der Asymmetrieparameter q an den Kernen 35Cl und 133Cs bestimmt. Die Temperaturabhangigkeit von C, ist fur beide Kerne mit einem negativen Temperaturkoeffizienten linear. Ein scharfer Knick von v ( '~~C S ) bei 342 K wird durch die Anderung der relativen Werte der Tensorkomponenten qij des elektrischen Feldgradienten am 133Cs verursacht. Die Temperaturabhangigkeit von qij wird bezuglich der Anisotropie der thermischen Ausdehnung diskutiert und eine numerische Berechnung des thermischen Ausdehnungskoefizienten durchgefuhrt.

Solid-state NMR of quadrupolar halogen nuclei

“…Simulation of the chlorine MAS NMR spectra allowed for the determination of precise values of the chlorine chemical shift, C Q , and g Q values for all 13 salts. Included in this study were the perchlorates examined previously by Tarasov et al, and the C Q ( 35 Cl) values determined in this study differ slightly, with values of 0.585, 0.537, and 0.441 MHz, for CsClO 4 , RbClO 4 , and KClO 4 , respectively [98,99,70]. The chemical shifts observed for the perchlorates range from 1029.6-1049.3 ppm (referenced to NaCl(s)); these are much greater than those observed for chlorides, due to increased paramagnetic contributions to the shielding tensor.…”

“…The chlorine site symmetry is approximately T d in all the perchlorates studied, but the small deviation from tetrahedral symmetry results in a nonzero QI at the chlorine nuclei in these salts. The chlorine C Q values are relatively small however, and they have been popular materials to study by chlorine SSNMR [70,[95][96][97][98][99][100][101][102][103].…”

“…The 35 Cl C Q s in these materials were found to be relatively small, as expected, with the largest being 1.120 MHz for phase III of dimethylammonium perchlorate. In 1991 and 1992, Tarasov et al released two publications which report on three alkali metal perchlorates [98,99]. Chlorine-35 SSNMR spectra were collected at 7.04 T under stationary condi- tions.…”

Solid-State 79/81Br NMR and Gauge-Including Projector-Augmented Wave Study of Structure, Symmetry, and Hydration State in Alkaline Earth Metal Bromides

“…Current reviews pertaining to the NMR-active quadrupolar halogen nuclides ,, underscore the significant ongoing advances in 35/37 Cl SSNMR spectroscopy. Recent progress is primarily due to the increasing availability of ultrahigh magnetic fields (i.e., B 0 > 18.8 T) and the development of advanced pulse sequences. – Prior to these developments, 35/37 Cl SSNMR studies were limited to systems where the chlorine environment was known to be nearly octahedral or tetrahedral. ,– Hence, the systems traditionally investigated using 35/37 Cl SSNMR were similar to those previously studied using 79/81 Br SSNMR. In the past five years, new insight into the relationship between 35/37 Cl SSNMR parameters and local molecular and electronic structure has been obtained for a range of interesting compounds, including amino acid hydrochlorides, – alkaline earth metal chlorides, , hydrochloride pharmaceuticals, group 4 organometallic chlorides, and halide-containing ionic liquids .…”

“…[34][35][36][37][38][39][40][41] Prior to these developments, 35/37 Cl SSNMR studies were limited to systems where the chlorine environment was known to be nearly octahedral or tetrahedral. 14,[42][43][44][45][46][47][48][49][50] Hence, the systems traditionally investigated using 35/37 Cl SSNMR were similar to those previously studied using 79/81 Br SSNMR. In the past five years, new insight into the relationship between 35/ 37Cl SSNMR parameters and local molecular and electronic structure has been obtained for a range of interesting compounds, including amino acid hydrochlorides, [51][52][53][54] alkaline earth metal chlorides, 55,56 hydrochloride pharmaceuticals, 57 group 4 organometallic chlorides, 58 and halide-containing ionic liquids.…”