CONFIGURATION AND CONFORMATION OF N,N'-DIARYLAMIDINES - A DIPOLE-MOMENT STUDY

Dipole moments of N,N'-diphenylformamidine and its para-halogen derivatives were measured in benzene solution. Since the prototropic rearrangement is degenerate, the dipole moments can be simply interpreted in terms of the E configuration on C=N and a conformational equilibrium on C-N. The two forms, Eap and Esp, are populated approximately in the 1 : 1 ratio: the former is the conformation found in the crystal. The dipole moments anticipated for individual conformations were calculated by vector addition of bond moments: the previously determined correction for conjugation was found unnecessary.