RING STRAIN-ENERGY AND ENTHALPY OF FORMATION OF OXIRANONE - AN AB-INITIO THEORETICAL DETERMINATION

The enthalpy of formation Delta H-f,298(0) for oxiranone is estimated as -190 +/- 10 kJ mol(-1) by means of ab initio molecular orbital calc ulations at the QCISD(T)=full/6-311G(2df,p)//MP2=full/6-311G(d,p) leve l of theory, corresponding to a conventional ring strain energy of 169 kJ mol(-1). The QCISD(T) calculated enthalpy of formation of cyclopro panone is 6.3 kJ mol(-1). The oxiranone ring is probably slightly less strained than the cyclopropanone ring.