Combinatorial Approach to the Catalytic Hydrosilylation of Styrene Derivatives: Catalyst Systems Composed of Organoiron(0) or (II) Precursors and Isocyanides

(COT)2Fe and the open ferrocenes (MPDE)2Fe (MPDE = η5-3-methylpentadienyl) and (DMPDE)2Fe (DMPDE = η5-2,4-dimethylpentadienyl) were found to function as catalyst precursors for the hydrosilylation of alkenes in the presence of auxiliary ligands. Screening trials determined that the optimal catalyst system was composed of (COT)2Fe and adamantyl isocyanide, allowing the selective hydrosilylation of styrene derivatives with trisubstituted hydrosiloxanes and a polydimethylsiloxane bearing Me2SiH moieties as the end groups. Under the appropriate conditions, the dehydrogenative silylation side reaction was completely suppressed, and the reaction TON exceeded 5000.