Reaction of ethyl lithiodiazoacetate with the cationic [Fe(arene)Cp] complexes 1 and 2 produces σ-adducts 6 and 7. Upon treatment with a catalytic amount of Rh₂(OAc)₄ in CH₂Cl₂, the adducts are transformed to metallocarbenes, which react further by 1,2- hydrogen migration. While reaction of 6 results in a mixture of equilibrating E and Z stereoisomers 8 and 9, a single product (10) is obtained from 7.