[(Indenyl)Ru(biphop-F)](+): A Lewis Acid Catalyst That Controls both the Diene and the Dienophile Facial Selectivity in Diels-Alder Reactions This work was supported by the Swiss National Science Foundation (FNS grant 20-59374.99) and The Ministère des Affaires Etrangères from France (Lavoisier grant to V.A.). biphop-F=1,2-bis[bis(pentafluorophenyl)phosphanyloxy]-1,2-diphenylethane.