($ Urene) tricarbonylchromium complexes play an important role in organometallic chemistry, which stems from their particular reactivity as it has been described in numerous reviews. l Their easy preparation has promoted series of studies of their ability to form stabilized benzylic anion^^-^ and cation^,^ to react in various ways with nucleophile^,^ to be easily metalated, 5 and to be active catalysts in hydrogenation reactions. 6
