Reactions of Cationic Piano Stool Iron Complexes Containing Phosphorus Ligands with Phosphorus Ylide

Abstract

Reactions of PF6- salts of cationic piano stool iron complexes with a phosphorus ylide, CH2PPh3, were examined. In the reaction of the dicarbonyl complex [Cp(CO)2FeL]+ (L = P(OMe)3, P(OEt)3, PPh2(OMe)), Cp(CO)LFe{C(O)CHPPh3} is formed by the nucleophilic attack of the carbene carbon of CH2PPh3 on the carbonyl carbon of the complex. In contrast, the reaction of the monocarbonyl complex [Cp(CO)LFe{P(OR)3}]+ (L = P(OMe)3, R = Me; L = PMe3, R = Me; L = P(OEt)3, R = Et) yields Cp(CO)LFe{P(O)(OR)2} by the Arbuzov-like dealkylation reaction. [Cp(PMe3)2Fe{P(OMe)3}]+, having no CO ligand, also exhibits the Arbuzov-like dealkylation reaction under forced conditions. These results indicate that increasing the back donation ability from a central transition metal to a ligand induces a change in the reaction site from a carbonyl carbon in a CO ligand to an α-carbon in a phosphite ligand. In the reaction of [Cp(CO)2Fe{PPh2H}]+, proton abstraction from the PPh2H ligand takes place to give a phosphide complex Cp(CO)2FePPh2.