A CCSD(T) INVESTIGATION OF CARBONYL OXIDE AND DIOXIRANE - EQUILIBRIUM GEOMETRIES, DIPOLE-MOMENTS, INFRARED-SPECTRA, HEATS OF FORMATION AND ISOMERIZATION ENERGIES

A CCSD and CCSD(T) investigation of carbonyl oxide (1) and its cyclic isomer dioxirane (2) has been carried out employing DZ + P and TZ + 2P basis sets. Calculated geometries, charge distributions, and dipole moments suggest that 1 possesses more zwitterionic character (CCSD(T) dipole moment 4 D) than has been predicted. 1 can be distinguished from 2 by its infrared spectrum as indicated by CCSD (T) frequencies, intensities, and isotopic shifts. The heats of formation DELTAH(f)0(298) for 1 and 2 are 30.2 and 6.0 kcal/mol, respectively; the CCSD(T) barrier to isomerization from 1 to 2 is 19.2 kcal/mol. Decomposition of 1 and 2 can lead to CO, CO2, H2O, H-2 but not to free CH2, O2 or O. Both isomers should be powerful epoxidation agents in the presence of alkenes, but they should differ in their ability to form cyclopropanes with alkenes.