Conformational energy surfaces of triplet-state isomeric methyloxiranes

A conformational study was carried out on the three ring-opened structures of triplet methyloxirane with a minimal Gaussian basis set, within the unrestricted Hartree–Fock framework. For the two structures energy surfaces E(θ₁, θ₂) were generated, where θ₁ measures the methyl rotation and θ₂ is associated with the torsion about the other C? C bond. For the third structure an energy hypersurface E(θ₁, θ₂, θ₃) was generated, where energy was a function of methyl rotation θ₁ and two nonequivalent C? O rotations θ₂ and θ₃. Analysis of the surfaces revealed the locations and relative energies of the critical points (minima, saddle points, and maxima). The overall stereochemical finding was that these ring-opened triplet C₃H₆O species possessed rather flexible structures.