Stoichiometric vs Catalytic MeLi Reaction with the Mixture of (ẽ 5 ‐C 5 H 5 )Fe(CO) 2 l and P(OR) 3 : Nucleophilic Methylation vs Arbuzov‐Like Dealkylation

The reaction of stoichiometric MeLi with the 1:1 mixture of (ẽ 5 ‐C 5 H 5 )Fe(CO) 2 I/P(OR) 3 (R = Me, Et, and Ph) at −78°C changes the bonding mode between metal and ring from (ẽ 5 ‐C 5 H 5 ) to (ẽ 4 ‐ exo ‐MeC 5 H 5 ) and the oxidation state of metal from Fe(II) to Fe(O), the novel complexes (ẽ 4 ‐ exo ‐MeC 5 H 5 )Fe(CO) 2 P(C)R) 3 being obtained in 45‐57% yields. The reaction of trace MeLi with the 1:1 mixture of (ẽ 5 ‐C 5 H 5 )Fe(CO) 2 I/P(OMe) 3 at −78°C results in 70% yield of the phosphonate complex (ẽ 5 ‐C 5 H 5 )Fe(CO) 2 P(O)(OMe) 2 which is an Arbuzov‐like dealkylation product from the cationic intermediate [(ẽ 5 ‐C 5 H 5 )Fe(CO) 2 P(OMe) 3 + ] and the iodide. The amines could assist the Arbuzov‐like dealkylation of [(ẽ 5 ‐C 5 H 5 )Fe(CO) 2 P(OMe) 3 + ] [PF 6 − ] where iron‐carbamoyl intermediates are likely involved in the case of primary amines.