Electron Spin Resonance Study of the Conformations of Anion Radicals derived from Some Thermochromic Ethylenes

Abstract

Electron spin resonance (ESR) spectra of the anion radicals of 10 (9H)-xanthene-9-ylidene-9 (10H)-anthracenone, 10-diphenylmethylene-9 (10H)-anthracenone, 9-diphenylmethylene-9H-xanthene, 9, 9'-bixanthene and diphenylfulvene were measured. These compounds, except for diphenylfulvene, are thermochromic ethylenes. On the basis of calculation of the spin densities by McLachlan's method and h. f. s. analysis of the ESR spectra, the anion radicals were found to be substantially twisted about the central double bond.