Friedel-Crafts acylation of W(CO)5-complexes of azaferrocenes

Blocking of the lone pair of electrons on the nitrogen in azaferrocene by co-ordination to the W(CO)5 moiety enables Friedel-Crafts acylation of this heteroferrocene. W(CO)5-complexes of azaferrocene and 2,5-dimethylazaferrocene react with acetyl- and propionyl chloride or acetic anhydride in the presence of aluminium chloride in dichloromethane at r.t. to give W(CO)5-complexes of 1′-acylazaferrocenes in 10–50% isolated yields. The low yields presumably result from instability of the products in the reaction medium. The X-ray structure of the complex of 1′-acetylazaferrocene has been determined.