MeLi reactions with the electrophile system of (eta(5)-C5H5)Fe(CO)(2)I/P(OMe)(3): The roles of MeLi as reductant, nucleophile, and base

The three roles of MeLi-nucleophile, base and reductant-could be revealed b y the electrophile system of (eta(5)-C5H5)Fe(CO)(2)I (1) and P(OMe)(3). The addition of MeLi dropwise without delay to the 1:1 mixture results in (eta (4)-exo-MeC5H5)Fe(CO)(2)P(OMe)(3) (3), where MeLi is a reductant at the fir st stage and then a nucleophile at the second stage. On the other hand, the addition of a catalytic amount of MeLi to the mixture of 1 and excess P(OM e)(3), followed by the MeLi/MeI sequence after a delay time, results in the formation of [eta(5)-C5H4-{P(O)(OMe)(2))}]-Fe(CO) {P(OMe)(3)}Me (7), where MeLi is a reductant at the initial stage and a base at the latter stage.