VII-G-3 Reaction of Cationic Piano Stool Iron Complexes Containing Phosphorus Ligands with Phosphorus Ylide

Hiroshi NAKAZAWA (Hiroshima Univ. and IMS), Yoshiko UEDA (Hiroshima Univ.), Keiichi NAKAMURA (Hiroshima Univ.) and Katsuhiko MIYOSHI (Hiroshima Univ.)

[Organometallics 16, 1562 (1997)]

Reactions of PF6- salts of cationic piano stool iron complexes with phosphorus ylide, CH2PPh3, were examined. In the reaction of dicarbonyl complex [Cp(CO)2FeL]+ (L = P(OMe)3, P(OEt)3, PPh2(OMe)), Cp(CO)LFe{C(O)CH=PPh3} is formed by the nucleophilic attack of the carbene carbon of CH2PPh3 on the carbonyl carbon of the complex. In contrast, the reaction of 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 forcing 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 (alpha)-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.


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