AB-INITIO STUDY OF STABILITY AND STRAIN OF CYCLOPROPANE AND ITS DERIVATIVES

The peculiar properties of the three-membered ring (C3 ring) in cyclopropane and its derivatives are due to characteristic bonding and electronic effects. Contraction of the atomic orbitals (AO's) composing the C-C bonding molecular orbitals (MO's) of a1 symmetry favors stability of the C3 ring. Expansion of the e' HOMO AO's contributes to the formation of peripheral ''pseudo-pi bonds''. The stability of the C3 ring also correlates with substitution of the ring.