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 (eta(5)-C5H4R)Fe(CO)(2)SiR'(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 = C3H5SiMe2SiMe3, R'(3) = Ph-3 (la); C5H5R = C5H5SiMe2SiMe2Ph, R'(3) = Ph-3 (1h); C5H5R = C5H5SiMe2SiMePh2, = Ph-3 (1f); C5H5R = C5H5SiMe2SiPh3, R'(3) = Ph-3 (1d); C5H5R = C(5)H(5)SiPh(2)StPh(3), R'(3) = Ph-3 (1e); C5H5R = C5H5SiMe3, R'(3) = Ph-3 (1o; C5H5R = C5H6, R'(3) = Ph-3 (1g);C5H5R = CsHsMe, R'(3) = Ph3 (1h);C5H5R = C5H5CH2Ph, R'(3) = Ph-3 (1i);C5H5R = MeC5H4SiM03, R'(3) = Ph3 (10; C5H5R=C9H8, R'(3) = Ph3 (1k);C5H5R = C5H5SiMe2SiMe2Ph, R'(3) = Me2Ph (1i); C5H5R = C5H5SiMe2Ph3, R'(3) = Me2Ph (1m); C5H5R = C(5)H(5)SiPh(2)StPh(3), R'(3) = Me2Ph (In);C5H5R = C5H5CH2Ph, R'(3) = MezPh (10). A plausible mechanism involving interception of coordinatively unsaturated iron species (eta(4)-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.