Singlet-triplet energy gaps in fluorine-substituted methylenes and silylenes

We report singlet and triplet state splittings (ΔE_(ST)) for fluorineâ€substituted methylenes and silylenes using dissociationâ€consistent configuration interaction (CI) (based on generalized valence bond wave functions). These relatively simple CI calculations emphasize correlation consistency between the singlet and triplet states. Values of ΔE_(ST) for CH_2, CF_2, SiH_2, and SiF_2 are in excellent agreement with available experimental results, and we expect the predictions for the other cases CHF (14.5) and SiHF (41.3) to be equally accurate. This result strongly suggests that the correct choice among the experimental values for ΔE_(ST) of CHF is 14.7±0.2 kcal/mol. ; © 1990 American Institute of Physics. Received 13 March 1990; accepted 25 January 1990. We wish to acknowledge the partial support of the National Science Foundation under Grant Nos. CHE87-11567 (J.L.B.) and CHE83-18041 (W.A.G.). ; Published - SHIjcp90c.pdf