Functionalised acyl ferrocenes: Crystal and molecular structures of 4-aminobenzoylferrocene, 4-hydroxybenzoylferrocene and 1,1′-bis(4-hydroxybenzoyl)ferrocene

Improved methods of synthesis are reported for FcCOC₆H₄F-4 1a, FcCOC₆H₄OMe-4 1b and Fcd(COC₆H₄OMe-4)₂ 2b [Fc = (C₅H₅)Fe(C₅H₄); Fcd = (C₅H₄)Fe(C₅H₄)]: demethylation of 1b and 2b, using AlCl₃ in 1,1,2-trichloroethane, yields FcCOC₆H₄OH 1f and Fcd(COC₆H₄OH)₂ 2f respectively. Acylation of ferrocene using 4-phthalimidobenzoyl chloride yields 4-(phthalimidobenzoyl)ferrocene 1c, hydrazinolysis of which yields FcCOC₆H₄NH₂-4 1d. Crystal structures are reported for 1d, 1f and 2f: in 1d and 1f the molecules are linked into spiral chains by means of N-H ⋯ O=C and O-H ⋯ O=C hydrogen bonds respectively; in 2f the O-H ⋯ O=C hydrogen bonds link the centrosymmetric molecules into continuous two-dimensional nets, two independent sets of which are interwoven.