Unexpected reactivity of functionalized lewis base stabilized silanediyl transition metal complexes toward organolithium nucleophiles

Article abstract of DOI:10.1021/om00008a056

(Organosilanediyl)chromium(0) pentacarbonyl complexes, [2-(Me₂NCH₂)C₆H₄]RSi=Cr(CO) ₅ (R = Me, Ph, t-Bu, Ph-C≡C-, Me₃Si-C≡C-), are obtained in good yield through the coupling reactions of (arylhydrogenosilanediyl)chromium(0) pentacarbonyl complex [2-(Me₂NCH₂)C₆H₄]HSi=Cr(CO) ₅, with the corresponding organolithium nucleophiles. Unexpectedly, the chloro- and bromosilanediyl complexes [2-(Me₂NCH₂)C₆H₄]-XSi=Cr(CO) ₅ (X = Cl, Br) are unreactive, but the fluorosilanediyl complex is even more reactive than the hydrogenosilanediyl complex with methyllithium. Possible geometries of the intermediate resulting in frontside attack of the nucleophile upon a zwitterionic silicon species are discussed.