Carbon-13 Chemical Shift Tensors for Acylium Ions: A Combined Solid State NMR and Ab Initio Molecular Orbital Study

Autor:	Dewey H. Barich, James F. Haw, Teng Xu, John B. Nicholas,‡ and, Paul D. Torres
Rok vydání:	1997
Předmět:	Chemical shift Carbon-13 Ab initio General Chemistry Biochemistry Catalysis Ion chemistry.chemical_compound Colloid and Surface Chemistry chemistry Chemical bond Solid-state nuclear magnetic resonance Computational chemistry Magic angle spinning Physical chemistry Carbon monoxide
Zdroj:	Journal of the American Chemical Society. 119:396-405
ISSN:	1520-5126 0002-7863
DOI:	10.1021/ja962944n
Popis:	We report the principal components of the 13C chemical shift tensors for seven acylium ions, determined by both slow speed magic angle spinning (MAS) nuclear magnetic resonance (NMR) and theoretical methods. Experimentally, the acylium ions were prepared either by direct reaction of the parent acyl halides with metal halide powders, including frozen antimony pentafluoride, or by the reaction of alkyl halides with carbon monoxide on aluminum chloride (AlCl3). The generalization of our recent observation of the acetylium ion on AlCl3 to other cations is direct proof of free acylium ion intermediates in Friedel−Crafts acylation reactions. 13C CP MAS NMR spectra of the acylium ions were acquired at temperatures ranging from 83 to 298 K, and the principal components of the 13C chemical shift tensors were extracted by fitting the side band intensities of the MAS spectra. With the exception of the chloroacetylium ion, the acylium ions studied have isotropic 13C1 chemical shifts of 154 ± 1 ppm, but clear variatio...
Databáze:	OpenAIRE
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