Cationic ruthenium and iron complexes [CpM(PP)](+) (Cp = eta(5)-C5H5; M = Ru and Fe; PP = Ph2PCH2CH2PPh2, 2PPh(3)) can affect vinylidene rearrangement of general internal alkynes via the 1,2-migration of aryl and alkyl groups. Judging from the migratory aptitude of substituted aryl groups, the present reaction is viewed as an uncommon electrophilic rearrangement.