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Study of structures, energetics, IR spectra and 13C and 1H NMR chemical shifts of the conformations of isopropyl cation by ab initio calculations

✍ Scribed by Golam Rasul; Jonathan L. Chen; G.K. Surya Prakash; George A. Olah

Publisher: Elsevier
Year: 2011
Tongue: English
Weight: 896 KB
Volume: 964
Category: Article
ISSN: 2210-271X
DOI: 10.1016/j.comptc.2010.12.024

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✦ Synopsis

The C 2 conformation 3 was established to be the preferred conformation of the isopropyl cation. The calculated 13 C NMR chemical shifts of C 2 conformation 3 also agree very well with the experimental data. However, this is, in contrast with the recent claims by Fa ˘rcas ßiu and coworkers, who found that the preferred conformation of the isopropyl cation in ion pair with trihydrofluoroborate is C s . Computed IR spectra indicates that hyperconjugative stabilization is clearly evident due to the shorter C + -C bond lengths and larger C-C + -C bond angles in the isopropyl cation structure 3. The computed IR absorptions of 3 also indicate that the greatest degree of electron donation takes place from C-H bonds into the formally empty p-orbital of the central carbon.

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