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Spatial structure and NMR spectra of strained [2.2.2]cyclophanes
Author(s) -
Dodziuk Helena,
Ostrowski Maciej,
Ruud Kenneth,
Jaźwiński Jarosław,
Hopf Henning,
Koźmiński Wiktor
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.2402
Subject(s) - chemistry , chemical shift , coupling constant , ethylbenzene , molecule , computational chemistry , density functional theory , nmr spectra database , carbon 13 nmr , strain (injury) , spectral line , proton nmr , carbon 13 nmr satellite , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , fluorine 19 nmr , organic chemistry , benzene , medicine , physics , particle physics , astronomy
The chemical shifts and coupling constants in the NMR spectra of the title compounds are influenced by their strain and the proximity of the aromatic rings. These parameters are studied by density functional theory (DFT) calculations for 1–4 and measured for 3 and 4. We find that, in spite of the strain, the calculations reproduce the experimental values satisfactorily. This finding is of special importance for novel hypothetical molecules like hexahydrosuperphane 5 for their future identification and in searches of hydrocarbons exhibiting unusual NMR parameters. Our results demonstrate the influence of strain on the parameters studied. Most proton and carbon chemical shifts for the molecules under study having nonplanar aromatic rings differ considerably from the corresponding values for the relatively unstrained trimethylbenzenes and ethylbenzene. In addition, the calculated values of the coupling constants through three bonds in most cases do not follow Karplus relation. Copyright © 2009 John Wiley & Sons, Ltd.