Carbon-13 chemical shielding tensors in polycyclic aromatic compounds. 1. single-crystal study of pyrene

Journal Article · Wed Apr 29 04:00:00 EDT 1987 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00243a015· OSTI ID:6541111

Carter, C M; Alderman, D W; Facelli, J C; Grant, D M

The carbon-13 chemical shielding tensors measured in single-crystal pyrene are reported. The two internal bridgehead carbons have principal values of 197, 191, and -18 ppm and the four peripheral bridgehead carbons 213, 187, and -7 ppm with respect to liquid Me/sub 4/Si. The high field component of every tensor is determined to be perpendicular to the molecular plane, as in benzene. The protonated carbons have principal values similar to benzene, with the low-field components lying approximately along the C-H bonds. The rotation of the principal axes away from the C-H bond direction is measured experimentally and interpreted by quantum chemical calculations. By use of a MNDO wave function and the Pople model of chemical shielding, the magnitudes of the experimental in-plane components are reproduced very well and the calculated orientations of the principal axes are consistent with the experimental data. The results reported here demonstrate that the measurement of /sup 13/C shielding tensors in polycyclic aromatic compounds can be used as a measurement of the aromatic character of bonds adjacent to /sup 13/C nuclei.

• Research Organization: Univ. of Utah, Salt Lake City
• DOE Contract Number: FG02-86ER13510
• OSTI ID: 6541111
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 109:9; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
AROMATICS
CARBON 13
CARBON ISOTOPES
CHEMICAL SHIFT
CONDENSED AROMATICS
CRYSTALS
DATA
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FUNCTIONS
HYDROCARBONS
INFORMATION
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MONOCRYSTALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ORGANIC COMPOUNDS
POLYCYCLIC AROMATIC HYDROCARBONS
PYRENE
RESONANCE
STABLE ISOTOPES
TENSORS
WAVE FUNCTIONS