Carbodicarbenes: Divalent Carbon(0) Compounds

Polarization of CC bonds is the trick! A “push–push” polarization of the double bonds stabilized the nonlinear allene 1 a (∢_CCC 134.8(2)°), which can be described as carbodicarbene 1 b. A similar behavior has been observed for 1,3-dimethyl-2-methyleneimidazoline, which can be seen as an olefin 2 a or an ylide 2 b. Both compounds 1 and 2 act as interesting electron-rich η¹ ligands for transition metals.