Nuclear magnetic resonance study of dipolar contribution to the ground state in a series of fulvenes
A series of fulvenes derived from isodicyclopentadiene has been prepared and their n.m.r. spectra studied. The simple low-field spectrum enabled immediate assignment of Hα and both Hγ-cis. and Hγ-trans. The shifts are correlated with π-electron densities calculated for a model compound and the transmission of charge from the α-carbon to the five-membered ring was found to be between that for styrenes and trans-cinnamic acids.