Treatment of CpFe(CO)2SiR3 (Cp = ηC5H5; R3 = pTol2Cl, pTol2H, pTol2Me, MePh(1-Nap), and (N-C5H11)2H; 1-NaP = 1-naphthyl) with LiAlH4 in ether or THF at room temperature gave CH3SiR3 as the major product in moderate to high yield together with HSiR3. Reaction of CpFe(CO)2SiMes2H with LiAlH4 afforded only H2SiMeS2. Labeling experiments using LiAlD4 give the deuterated methylsilane. These results proved that the hydrogen source for the methyl group is LiAlH4. Furthermore, the reduction of CpFe(*CO)2SipTol2R′ (*C = 13C enriched; R′ = H, Me) produced *CH3SipTol2R′ where the methyl group introduced on Si was 13C-enriched. These experimental results suggested that the carbonyl ligand was reduced by LiAlH4 and coupled with the silyl group to give the methylsilane. Cp*Fe(CO)2SipTol2H (Cp* = η5-C5Me5), having a Cp* ligand which is bulkier and more electron-donating than a Cp ligand did not react with LiAlH4 at room temperature, but it did so at 50°C to give CH3SipTol2H and HSipTol2H, probably because nucleophilic attack of LiAlH4 at a carbonyl ligand was retarded both sterically and electronically by the Cp* ligand. When the reactions were performed in sealed NMR tubes and monitored by NMR tubes and monitored by NMR spectroscopy, the signals due to the anionic complexes Li-[CpFe(CO)(CH3)SipTol2R′]- were observed in addition to those of silane products. These anionic complexes are considered not to be intermediates but to be byproducts because the anionic complexes did not change to methylsilanes on heating. The anionic complexes reacted with MeOH and MeI to give hydrosilanes HSipTol2R′ and methylsilanes CH3SipTol2R′, respectively.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry