Fulvenes and thermochromic ethylenes. Part XLIV. Shielding effects in diphenylmethylenefluorene, fluorenylidenetriphenylphosphorane, and related substances

Abstract

The nuclear magnetic resonance spectra of a number of dibenzofulvenes, fluorenylidenephosphoranes, and dibenzoheptafulvenes have been studied, and the effect of the following factors has been evaluated: (i) the planarity of the molecule; (ii) the interaction between the 1,8-hydrogen atoms, and the π-electrons of the fulvenic double bond and of the phenyl rings in the ω-position; (iii) the inductive effect of the dipole of the fulvenic bond on the 1,8-hydrogen atoms.