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Determination of the methyl group rotation energy barrier in some substituted tricyclo [3.1.0.0 2,6 ]hexanes by carbon‐13 spinlattice relaxation
Author(s) -
Mellink W. A.,
Kaptein R.
Publication year - 1980
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270130413
Subject(s) - chemistry , carbon skeleton , bent molecular geometry , methyl group , hexane , relaxation (psychology) , rotation (mathematics) , spectral line , group (periodic table) , crystallography , enone , stereochemistry , nuclear magnetic resonance , organic chemistry , physics , geometry , psychology , social psychology , mathematics , astronomy
The resonances in the 13 C NMR spectra of 1,2,5,6‐tetramethyl‐3,4‐dimethylenetricyclo[3.1.0.0 2,6 ]hexane and the corresponding enone and dione have been assigned. The rotation energy barriers of the methyl groups have been determined from 13 C spin‐lattice relaxation time measurements; barriers of 6.7–10.9 kJ mol −1 have been found. Since X‐ray data have shown that the skeleton bonds are bent away from the CCH 3 axis by angles of over 120°, only minor interactions occur between adjacent methyl groups. Therefore, these barriers are mainly governed by interactions with the CC skeleton bonds.