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Complete assignment and additivity rule for 1 H and 13 C chemical shifts of non‐planar, nonacyclic aromatic hydrocarbons
Author(s) -
Ueda Toyotoshi,
Iwashima Satoshi,
Aoki Junji,
Takekawa Minoru
Publication year - 1995
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.1260330203
Subject(s) - chemistry , homonuclear molecule , chemical shift , heteronuclear molecule , ring (chemistry) , two dimensional nuclear magnetic resonance spectroscopy , benzene , ring current , spectral line , nmr spectra database , conjugated system , additive function , computational chemistry , nuclear magnetic resonance spectroscopy , crystallography , stereochemistry , molecule , organic chemistry , physics , polymer , earth's magnetic field , mathematical analysis , mathematics , quantum mechanics , astronomy , magnetic field
Complete assignments of 1 H and 13 C NMR spectra were made for heptacyclic peropyrene and five isomers of dibenzoperopyrenes, using 2D correlation spectroscopic techniques of homonuclear HH‐COSY and NOESY and heteronuclear CH‐COSY and HMBC methods. New additivity rules of 1 H and 13 C chemical shift values were established for compounds having two types of benzene ring condensation. All 1 H chemical shifts were satisfactorily interpreted by a very simple magnetic point dipole model. This model includes net contributions from each constituent benzene ring due to the ring current anisotropy and permits some ring planes to deviate from the mean molecular plane. The conjugated ring currents are consistent with the chemical shifts. Thus, the aromatic properties are normal even if the molecular skeleton is considerably deformed and becomes non‐planar.