MeLi Reactions with the Electrophile System of (η5-C5H5)Fe(CO)2I/P(OMe)3:  The Roles of MeLi as Reductant, Nucleophile, and Base

The three roles of MeLinucleophile, base and reductantcould be revealed by the electrophile system of (η5-C5H5)Fe(CO)2I (1) and P(OMe)3. The addition of MeLi dropwise without delay to the 1:1 mixture results in (η4-exo-MeC5H5)Fe(CO)2P(OMe)3 (3), where MeLi is a reductant at the first 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(OMe)3, followed by the MeLi/MeI sequence after a delay time, results in the formation of [η5-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.