Abstract: The reactions of 2-phenylmethylenecyclopropane (1) and 2, 2- diphenylmethylenecyclopropane (7) with a variety of iron-carbonyl reagents are presented. The stereochemistry of ring opening of 1 to (phenyltrimethy1enemethane) iron tricarbonyl is elucidated by stereospecific deuterium labeling. The deuterium labeling also allows information to be gained about the conversion of 1 to ((E)-1-phenylbutadiene) iron ...