Stoichiometric vs Catalytic MeLi Reaction with the Mixture of (ẽ5-C5H5)Fe(CO)2l and P(OR)3: Nucleophilic Methylation vs Arbuzov-Like Dealkylation

Abstract

The re ac tion of stoichiometric MeLi with the 1:1 mix ture of ( η 5 - C 5H5)Fe(CO) 2I/P(OR) 3 (R = Me, Et, and Ph) at -78 °C changes the bond ing mode be tween metal and ring from ( η 5 - C 5H5) to ( η 4 -exo -Me C 5H5) and the ox i da tion state of metal from Fe(II) to Fe(0), the novel com plexes ( η 4 -exo -Me C 5H5)Fe(CO) 2P(OR) 3 be ing ob tained in 45-57% yields. The re ac tion of trace MeLi with the 1:1 mix ture of ( η 5 - C 5H5)Fe(CO) 2I/P(OMe) 3 at -78 °C re sults in 70% yield of the phosphonate com plex ( η 5 - C 5H5)Fe(CO) 2P(O)(OMe) 2 which is an Arbuzov-like dealkylation prod uct from the cationic in ter me di ate [( η 5 - C 5H5)Fe(CO) 2P(OMe) 3 + ] and the io dide. The amines could as sist the Arbuzov-like dealkylation of [( η 5 - C 5H5)Fe(CO) 2P(OMe) 3 + ][P F 6 - ] where iron-carbamoyl in ter me di ates are likely in volved in the case of pri mary amines.