ISSN:
0948-5023
Keywords:
Keywords Hydronium tetrafluoroborate, Ion pairs, Ion clusters, Ab initio calculations, GIAO-B3LYP chemical shift calculations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Hydronium tetrafluoroborate ion pairs, H3O+·BF4 - have been shown computationally to be unstable toward decomposition, in the absence of solvation or electrostatic interactions existing in crystals. As the proton NMR spectrum of a hydronium salt with the octanesulfonate-antimony pentachloride complex anion was reported in freon solution, we investigated the hypothesis that larger ionic clusters were present in the nonpolar solvent. It was found that the dimer (H3O+·BF4 -)2 was stable at the MP2/6-31G* level. GIAO-B3LYP chemical shift calculations with the same basis set and also with the 6-31G**, 6-31++G**, 6-311++G**, dzvp, tzp, tz2p, and qz2p basis sets conducted on the hydronium fluoroborate dimer reproduce the main features of the experimental spectrum: the existence of two signals with a two-to-one intensity ratio and the more intense resonance at higher frequency (more deshielded). The alternative structures, of hydronium tetrafluoroborate ion pairs with one and with two hydrogen bonds between anion and cation, give calculated chemical shifts which are farther from the experimental values.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00010726
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