Tetraphenylphosphonium Perchlorate

Vittal, J. J.; Dean, P. A. W.

doi:10.1107/s0108270196010980

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…This may be an order−disorder transition for half of the ClO 4 - anions in the solvate unit cell (Figure ). Such ordering of the ClO 4 - anions occurs in a solid−solid phase change for Ph 4 PClO 4 . The “freezing-in” of higher temperature salt disordered states on cooling has been noted by vibrational spectroscopy .…”

Section: Resultsmentioning

confidence: 92%

LiClO₄ Electrolyte Solvate Structures

et al. 2003

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Two crystalline phases, (monoglyme)2:LiClO4 and (diglyme)2:LiClO4, have been isolated and characterized. The former consists of contact ion pairs in which the anions have bidentate coordination to the Li+ cations, while the latter consists of fully solvated Li+ cations in which the cations and anions do not directly interact. The two structures are useful as models for solvate structures in concentrated electrolyte mixtures. In particular, the phase behavior and solvate structures of solvent−salt mixtures are informative when coupled with vibrational spectroscopic analysis of ionic association behavior in solutions.

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Section: Resultsmentioning

confidence: 92%

LiClO₄ Electrolyte Solvate Structures

et al. 2003

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“…A single-crystal X-ray diffraction study has not been conducted on this molecule; there are, however, a number of structurally analogous molecules which have been characterized by single-crystal and powder diffraction and which supposedly share the same crystallographic space groups and basic unit cell dimensions as AsPh 4 ReO 4 . Among these are the tetraphenylphosphonium, tetraphenylantimony, and tetraphenylbismuth perchlorates, whose single-crystal structures have all been determined, as well as the tetraphenylarsonium and tetraphenylphosphonium permanganates which were studied by powder diffraction. − All these salts show the same tetragonal space group I 4̄ and similar unit cell dimensions, as well as distorted XO 4 - tetrahedra possessing S 4 symmetry. It also follows from these structures that unlike in the scheelites, the ReO 4 - anions in AsPh 4 ReO 4 are far removed from one another by large tetraphenylarsonium cations.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Effects on the Powder Line Shapes of Half-Integer Quadrupolar Nuclei: A Solid-State NMR Study of XO₄^- Groups

2001

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Multinuclear solid-state nuclear magnetic resonance studies (185/187Re, 55Mn, 75As, and 1H NMR) were undertaken on a series of polycrystalline inorganic salts incorporating diamagnetic XO4 - groups, X being a half-integer quadrupolar nucleus. Exploiting data acquisition protocols that were recently developed for observing undistorted half-integer quadrupole central transitions, some of the largest quadrupole coupling constants reported to date by high field NMR were characterized (e 2 qQ/h ≈ 300 MHz). On repeating such measurements as a function of temperature, certain samples displayed reversible changes that could not be rationalized in terms of the usual temperature dependencies of the nuclear quadrupolar couplings. Instead, dynamic exchange processes between chemically or magnetically inequivalent sites had to be invoked. To quantitatively analyze these processes, the semiclassical Bloch−McConnell formalism for chemical exchange was extended to account for second-order quadrupole effects. Insight into the potential nature of the chemical dynamics was also obtained from quantum chemical calculations of the coupling parameters on model systems.

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“…The structure of (I) has previously been reported at 293 K (RT phase) as tetragonal, I4, a = 12.383 (3), c = 7.188 (2) A Ê , V = 1102.2 (5) A Ê 3 and Z = 2 (Vittal & Dean, 1996). The data we collected at 123 K (LT phase) also gave a tetragonal cell, space group I4, but with dimensions a = 17.0481 (4), c = 13.7568 A Ê , V = 2998.2 (2) A Ê 3 and Z = 8.…”

Section: Commentmentioning

confidence: 90%

“…A number of other similar salts have been found at room temperature to have crystal structures isomorphous with the RT phase of (I) (Couldwell, 1979;Vittal & Dean, 1996, and references therein). It would be reasonable to expect a number of these to undergo similar phase changes at low temperatures.…”

Section: Commentmentioning

confidence: 99%