ELECTRONIC PROPERTIES OF 3-MEMBERED RINGS .2. TRANSMISSION OF CONJUGATION BY CYCLOPROPANE RING

A series of p-fluoro-m′- and -p′-substituted 1,2-diphenylethanes (bibenzyls), 1,2-diphenylethylenes (stilbenes), and 1,2-diphenylcyclopropanes have been synthesized and their 19F nmr spectra determined in dilute benzene solution. A quantitative measure of the ability of the cyclopropyl ring to transmit conjugation in the ground electronic state has been made from a plot of the19F nmr shielding parameters vs. Taft´s σ˚ constant. The results of the present study show that the cyclopropyl ring is ~27% as effective as the vinyl moiety (relative to dimethylene) in its ability to transmit conjugation. © 1969, American Chemical Society. All rights reserved.