Potential energy surface of 1,6-methano[10]annulen-11-ylidene and its isomers

The potential energy surface of 1,6-methano[10]annulen-11-ylidene and its i somers has been investigated by density functional (BLYP and B3LYP) molecul ar orbital methods. These calculations indicate the lowest energy annulene; structure to be 56.9 kcal mol(-1) higher in energy than triplet 1-naphthylc arbene. These calculations, together with calculations on transition states connecting possible rearrangement products derived from this carbene, indi cate that the trapping products reported by Carlton et al. J. Am. Chem. Sec . 1978, 98, 6068-6070 arise from rearrangement of the annulene-carbene to a tricyclic isomer.