AM1 STUDY OF PHOTOELECTRON-SPECTRA .6. ALKOXYALLENES - INTERACTION OFDISTANT FRAGMENTS

A correlation was found between the group dipole moments of substituen ts determined from the dipole moments of ethylene derivatives and the second ionization potentials of allene derivatives corresponding to th e pi'-MO of the C(beta)-C(gamma) bond. It was shown that the concept o f the effect of the substituent field cannot completely explain the ob served phenomena, and the energies of the second ionic states of bromo allene and alkoxyallenes are lowered because of the interaction betwee n nonbonded fragments through the sigma systems of the compounds. It h as been found that, in terms of orbital approximation, this interactio n causes electronic destabilization of the anti-planar (trans) conform ers of methoxyallene and methyl vinyl ether compared to their sin-plan ar (cis) forms.