Carbodicarbenes: Divalent Carbon(0) Compounds



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Polarization of C[DOUBLE BOND]C bonds is the trick! A “push–push” polarization of the double bonds stabilized the nonlinear allene 1 a (∢C[BOND]C[BOND]C 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.