RESTRICTED ROTATION INVOLVING THE TETRAHEDRAL CARBON .23. COMPARISON OF BARRIERS TO ROTATION OF 9-(2-ISOPROPYLPHENYL)FLUORENE OBTAINED BY H-1 DNMR, C-13 DNMR, DOUBLE-RESONANCE AND KINETIC MEASUREMENTS

Rates of rotation about the C‐9‐C‐ar bond of 9‐(2‐isopropylphenyl) fluorene were measured by 1H DNMR, 13C DNMR, double resonance, and a kinetic method. The kinetic data obtained by these methods were critically examined. The DNMR methods afforded satisfactory results if rate data obtained by total line shape analyses of complicated signals with couplings were used, and those derived from simple patterns were abandoned. Agreement among the data yielded by the four different methods was excellent, provided that the data which might contain dubiously large errors were excluded. Copyright © 1979 Heyden & Son Ltd.