The iron atom is bonded to four carbons of the methylenecyclopropene ligand and three carbonyl groups. It is noteworthy that both r (C1C2)(1.479 A) and r (C3C4)(1.397 A)(to a lesser extent) are elongated by comparing with the corresponding bonds of 1 (1.323 and 1.332 A, respectively) as determined by microwave spectra. 3c In contrast, the analogous bond distances in r (CIC3)
