Structures of C 3H 6O species in the triplet state: Methyloxirane, propanal, acetone, methyl vinyl ether and propenol

Abstract

The geometries of thirteen triplet C 3H 6O species, plus methyloxirane and propene in the ground state, have been completely optimized by analytic gradient (force) techniques at both the minimal STO-3G and split valence 3-21G basis set levels. Single calculations using the 6-31G* polarized basis set were performed for each 3-21G optimum structure. With the exception of bond angles at oxygen and the pyramidality at carbon radical centers, the geometries obtained with the two basis sets differ little. Except for the propene +O( 3 P) atom, the addition of d orbitals has little effect on the relative energies compared to the 3-21G energy differences (Δ E), but both were markedly different from the STO-3G results. Whereas the latter Δ E values covered a range of almost 40 kcal mol −1, this range was reduced to 24.5 and 22.4 kcal mol −1 at the 3-21G and 6-31G −* levels, respectively.