Stoichiometric vs catalytic MeLi reaction with the mixture of (eta(5)-C5H5)Fe(CO)(2)I and P(OR)(3): Nucleophilic methylation vs Arbuzov-like dealkylation

The reaction of stoichiometric MeLi with the 1:1 mixture of (eta(5)-C5H5)Fe (CO)(2)I/P(OR)(3) (R = Me, Et, and Ph) at -78 degrees C changes the bonding mode between metal and ring from (eta(5)-C5H5) to (eta(4)-exo-MeC5H5) and the oxidation state of metal from Fe(II) to Fe(0), the novel complexes (eta (4)-exo-MeC5H5)Fe(CO)(2)P(OR)(3) being obtained in 45-57% yields. The react ion of trace MeLi with the 1:1 mixture of (eta(5)-C5H5)Fe(CO)(2)I/P(OMe)(3) at -78 degrees C results in 70% yield of the phosphonate complex (eta(5)-C 5H5)Fe(CO)(2)P(O)(OMe)(2) which is an Arbuzov-like dealkylation product fro m the cationic intermediate [(eta(5)-C5H5)Fe(CO)(2)P(OMe)(3)(+)] and the io dide. The amines could assist the Arbuzov-like dealkylation of [(eta(5)-C5H 5)Fe(CO)(2)P(OMe)(3)(+)][PF6-] where iron-carbamoyl intermediates are likel y involved in the case of primary amines.