Premium
Theoretical investigation on multinuclear NMR chemical shifts of some tris(trifluoromethyl)boron complexes
Author(s) -
Zhang Jun,
Cai Shuhui,
Chen Zhong
Publication year - 2009
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2438
Subject(s) - chemical shift , chemistry , trifluoromethyl , boron , fluorine 19 nmr , fluorine , atomic orbital , crystallography , computational chemistry , polarizability , carbon 13 nmr , nuclear magnetic resonance spectroscopy , molecule , stereochemistry , organic chemistry , alkyl , physics , quantum mechanics , electron
Tris(trifluoromethyl)boron complexes have unusual properties and may find applications in many fields of chemistry, biology, and physics. To gain insight into their NMR properties, the isotropic 11 B, 13 C, and 19 F NMR chemical shifts of a series of tris(trifluoromethyl)boron complexes were systematically studied using the gauge‐included atomic orbitals (GIAO) method at the levels of B3LYP/6‐31 + G(d,p)//B3LYP/6‐31G* and B3LYP/6‐311 + G(d,p)//B3LYP/6‐311 + G(d,p). Solvent effects were taken into account by polarizable continuum models (PCM). The calculated results were compared with the experimental values. The reason that the structurally inequivalent fluorine atoms in a specific species give a same chemical shift in experimental measurements is attributed to the fast rotation of CF 3 group around the BC(F 3 ) bond because of the low energy barrier. The calculated 11 B, 13 C(F 3 ), and 19 F chemical shifts are in good agreement with the experimental measurements, while the deviations of calculated 13 C(X, X = O, N) chemical shifts are slightly large. For the latter, the average absolute deviations of the results from B3LYP/6‐311 + G(d,p)//B3LYP/6‐311 + G(d,p) are smaller than those from B3LYP/6‐31 + G(d,p)//B3LYP/6‐31G*, and the inclusion of PCM reduces the deviation values. The calculated 19 F and 11 B chemical shieldings of (CF 3 ) 3 BCO are greatly dependent on the optimized structures, while the influence of structural parameters on the calculated 13 C chemical shieldings is minor. Copyright © 2009 John Wiley & Sons, Ltd.