Theoretical study of the low-lying triplet and singlet states of diradicals. 2. Cyclopentadienyltrimethylenemethane

Abstract

Cyclopentadienyltrimethylenemethane has low-lying singlet and triplet states of A 1 and B 2 symmetry. The geometries of these states have been optimized by means of the ROHF, UHF, and MCSCF methods. The two lowest energy states-the 3 B 2 ground state and the 1 A 1 state, lying 4.9 kcal/mol above the ground state-are predicted to be planar. The higher-lying 3 A 1 and 1 B 2 states are found to have nonplanar structures