Ethyl (Z)-4-ferrocenyl-2-(4-hydroxyanilino)-4-oxobutenoate

In the title compound, [Fe(C5H5)(C17H16NO4)], the O=C—C=C—N mean plane is twisted with respect to the mean planes of the benzene and substituted cyclopentadienyl rings by 44.2 (2) and 13.8 (3)°, respectively. Furthermore, the O=C—C=C—N mean plane and the O=C—O(ester) plane make a dihedral angle of 55.5 (6)°. Consistent with this large dihedral angle, the linking C—C bond [1.507 (6) Å] does not show any (delocalized) double-bond character.

In the title compound, [Fe(C 5 H 5 )(C 17 H 16 NO 4 )], the O C-C C-N mean plane is twisted with respect to the mean planes of the benzene and substituted cyclopentadienyl rings by 44.2 (2) and 13.8 (3) , respectively. Furthermore, the O C-C C-N mean plane and the O C-O(ester) plane make a dihedral angle of 55.5 (6) . Consistent with this large dihedral angle, the linking C-C bond [1.507 (6) Å ] does not show any (delocalized) double-bond character.

Experimental
Crystal data [Fe(C 5

Comment
Recently enaminones and related compounds have been used as ligands in coordination chemistry and have been extensively used as versatile synthetic intermediates that combine the ambident nucleophilicity of enamines with the ambident electrophilicity of enones for the preparation of a variety of heterocyclic systems including some natural products and analogues (Elassar & El-Khair, 2003;Kascheres, 2003).
As noted in the compounds previously reported, the O═ C-C═C-N moiety is planar and the bond lengths indicate electron delocalization (Shi et al., 2004). The O═C-C═C-N plane is twisted with respect to the benzene and substituted cyclopentadienyl rings by 44.2 (2) and 13.8 (3)° whereas the values in an analogous compound are 38.2 (2) and 2.5 (2)°( Prokop et al., 2001). Furthermore, the O═C-C═C-N plane and the O═ C-O plane make a dihedral angle of 55.5 (6)°w hich is greater than that (48.1 (4)°) of the analogous compound. Consistent with the large dihedral angle between the O═C-C═C-N plane and ester group, the C13-C14 bond, is typical of a single bond (C sp2 -C sp2 ), and therefore indicates that the ester group is not involved in the conjugation of the O═C-C═C-N moiety. Similarly, the C10-C11 bond suggests that the substituted cyclopentadienyl ring is not involved in the conjugation of the O═ C-C═C-N moiety (Shi et al., 2006).

Experimental
A mixture of ethyl 4-ferrocenyl-2, 4-dioxobutanate (1.3 g, 4 mmol) and 4-aminophenol (0.43 g, 4 mmol) in 20 ml of absolute ethanol was refluxed for 18 h. After removal of the solvent, the residue was purified by chromatography on silica gel using diethyl ether and dichloromethane (v/v, 1:10) as an eluant to give the title compound as a purple-red solid (m.p.