Genre
- Journal Article
Solid-state H-2 NMR powder spectra and T-1 longitudinal relaxation data have been collected for carceplexes containing benzene and acetonitrile guest molecules. Analysis of the data suggests that benzene rotates rapidly about its C-6 axis with an activation energy of 25.8 +/- 0.4 kJ mol(-1). In addition, it reorients about the C-4 axis of the carceplex cavity with a rate (ca. 10(6)-10(7) s(-1)) that is in the intermediate regime on the H-2 NMR spectral timescale in the temperature range T = 310-400 K. Lineshape simulations suggest that this reorientation has less than four-fold symmetry owing to unequal site populations, probably a reflection of the deviation from C-4 symmetry of the carceplex geometry. Acetonitrile reorients rapidly (much greater than 10(5) s(-1)) about a four-fold symmetric axis for T greater than or equal to 181 K.
UNIV BRITISH COLUMBIA,DEPT PHYS,VANCOUVER,BC V6T 1Z1,CANADA. UNIV BRITISH COLUMBIA,DEPT CHEM,VANCOUVER,BC V6T 1Z1,CANADA.
CAMBRIDGE; THOMAS GRAHAM HOUSE SCIENCE PARK MILTON ROAD, CAMBRIDGE, CAMBS, ENGLAND CB4 4WF
ROYAL SOC CHEMISTRY
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Source type: Electronic(1)
Language
- English
Subjects
- RESONANCE LINE-SHAPES
- SOLIDS
- Physics, Atomic, Molecular & Chemical
- complexation
- benzene
- Chemistry, Physical
- SPECTROSCOPY
- MOTIONS