A New Approach to Directly Synthesize (η5‑C5H4R)Fe(CO)2SiR′3 by Reaction of Cyclopentadienes with Pentacarbonyliron and Hydrosilanes

A new approach to the direct synthesis of Fe–Si-bonded complexes (η 5 -C5H4R)Fe(CO)2SiR′3 (1) by the reaction of cyclopentadienes C5H5R (2) with pentacarbonyliron in the presence of hydrosilanes R′3SiH (5) has been developed. Thus, when the reaction of 2 and pentacarbonyliron in refluxing p-xylene was performed in the presence of 5, the desired complexes were successfully obtained in good yields, providing a simple one-step synthetic route to obtain 1 from the readily available starting materials, wherein the substituents R and R′ could vary over a wide range: C5H5R = C5H5SiMe2SiMe3, R′3 = Ph3 (1a); C5H5R = C5H5SiMe2SiMe2Ph, R′3 = Ph3 (1b); C5H5R = C5H5SiMe2SiMePh2, R′3 = Ph3 (1c); C5H5R = C5H5SiMe2SiPh3, R′3 = Ph3 (1d); C5H5R = C5H5SiPh2SiPh3, R′3 = Ph3 (1e); C5H5R = C5H5SiMe3, R′3 = Ph3 (1f); C5H5R = C5H6, R′3 = Ph3 (1g); C5H5R = C5H5Me, R′3 = Ph3 (1h); C5H5R = C5H5CH2Ph, R′3 = Ph3 (1i); C5H5R = MeC5H4SiMe3, R′3 = Ph3 (1j); C5H5R=C9H8, R′3 = Ph3 (1k); C5H5R = C5H5SiMe2SiMe2Ph, R′3 = Me2Ph (1l); C5H5R = C5H5SiMe2Ph3, R′3 = Me2Ph (1m); C5H5R = C5H5SiPh2SiPh3, R′3 = Me2Ph (1n); C5H5R = C5H5CH2Ph, R′3 = Me2Ph (1o). A plausible mechanism involving interception of coordinatively unsaturated iron species (η4-C5H5R)Fe(CO)2 by oxidative addition of the Si–H bond is believed to be responsible for the preferred formation of the desired product.