Cobalt−Carbene Complex with Single-Bond Character: Intermediate for the Cobalt Complex-Catalyzed Cyclopropanation

Abstract
It is generally considered that metal−carbene carbon bonds in carbene complexes for cyclopropanation should be double-bonded; however, the theoretical and FT-IR analyses revealed that the cobalt−carbene carbon bond of the 3-oxobutylideneaminato or the salen-cobalt−carbene complexes was characterized as a single bond.