ABINITIO MCSCF AND CI CALCULATIONS OF THE SINGLET-TRIPLET ENERGY DIFFERENCES IN OXYALLYL AND IN DIMETHYLOXYALLYL

Ab initio MCSCF and multireference CI calculations predict a very small singlet-triplet energy splitting in oxyallyl (2). The largest calculations find the triplet to be the ground state by 1-2 kcal/mol. The reason for the small singlet-triplet energy difference in 2 is discussed. The pair of alkyl substituents in dimethyloxyallyl (3) are computed to confer a singlet ground state on this diradical. Multireference CI calculations, which include correlation between σ and π electrons, give a singlet-triplet energy separation in 3 of ~5 kcal/mol. © 1990, American Chemical Society. All rights reserved.