The development of organometallic chemistry over the past 25 years has led to extremely selective catalytic systems and to a greater understanding of their mechanisms. One area of particular interest has been the study of hydrogenation reactions (e.g. dienes to monoenes) using (η6−arene)tricarbonylchromium(0) complexes as catalysts.1–4The possibility of the catalytic liberation of functionalized arenes from the chromium centers in such compounds has also attracted the attention of synthetic organic chemists.5−6