Theoretical study of reactions of α-diimines with P(III) acid halides by semiempirical quantum-chemical methods

Stability of potential products of alpha-diimine reactions with P(III) acid halides was characterized by PM3 semiempirical quantum-chemical calculations with full geometry optimization. The energetic favorability of formation of diazaphospholene (oxodiazaphospholene) or diazaphospholane cyclic structures with an exocyclic diene system from acyclic diimines and cyclohexanediimine and the unfavorability of formation of similar structures from dihydropyrazines was demonstrated. Dihydropyrazines should prefer phosphorylation involving one of the C=N bond. The calculation results fairly agree with available experimental data and allow prognosis of the probability of formation of one or another structure in new reactions.