3-(3-Acetylanilino)-1-ferrocenylpropan-1-one

The title ferrocene-containing Mannich base, [Fe(C5H5)(C16H16NO2)], crystallizes with two independent molecules (A and B) in the asymmetric unit. Molecules A and B have similar conformations. The dihedral angles between the best planes of the benzene and substituted cyclopentadienyl rings are 88.59 (9) and 84.39 (10)° in A and B, respectively. In the crystal, the independent molecules form centrosymmetric dimers via corresponding N—H⋯O hydrogen bonds. The dimers further arrange via C—H⋯π and C—H⋯O interactions. There are no significant interactions between the A and B molecules.

The title ferrocene-containing Mannich base, [Fe(C 5 H 5 )-(C 16 H 16 NO 2 )], crystallizes with two independent molecules (A and B) in the asymmetric unit. Molecules A and B have similar conformations. The dihedral angles between the best planes of the benzene and substituted cyclopentadienyl rings are 88.59 (9) and 84.39 (10) in A and B, respectively. In the crystal, the independent molecules form centrosymmetric dimers via corresponding N-HÁ Á ÁO hydrogen bonds. The dimers further arrange via C-HÁ Á Á and C-HÁ Á ÁO interactions. There are no significant interactions between the A and B molecules.

Comment
Derivatives of ferrocene have attracted great interest due to their physical, chemical and biological properties (Togni & Hayashi, 1995). In the course of our studies of different ferrocene derivatives containing two or more heteroatoms, we have synthesized and determined the crystal structures of a series of 3-(arylamino)-1-ferrocenylpropan-1-ones (Damljanović et al. 2011Leka et al. 2012a. The present derivative 1ferrocenyl-3-(3-acetylphenylamino)propan-1-one, crystallizes with two independent molecules (A and B) in the asymmetric unit (Fig. 1). The cyclopentadienyl rings (Cp) within the Fc unit of molecules A and B take a nearly eclipsed geometry; the corresponding torsion angle C1-Cg1-Cg2-C6 has a value of 2.8 and 3.2°, respectively (Cg is centroid of the corresponding Cp ring). Both molecules display a conformation similar to that of previously reported derivatives containing meta-substituted phenyl rings.

Experimental
An aza-Michael addition of arylamines to a conjugated enone, acryloylferrocene, has been achieved by ultrasonic irradiation of the mixture of these reactants and the catalyst -montmorillonite K-10. This solvent-free reaction, yielding ferrocene containing Mannich bases (3-(arylamino)-1-ferrocenylpropan-1-ones), has been performed through the use of a simple ultrasonic cleaner. The details of the synthesis are described by Pejović et al. (2012b).

Refinement
H atoms bonded to C atoms were placed at geometrically calculated positions and refined using a riding model. C-H distances were fixed to 0.93, 0.97 and 0.96 Å for aromatic, methylene and methyl C atoms, respectively. The U iso (H) values were set to 1.2 times U eq of the corresponding aromatic and methylene C atoms. The U eq values of the H atoms attached to methyl C atoms were set equal to 1.5 times U eq of the parent atom. H atoms attached to N atoms were refined supplementary materials isotropically.

Figure 1
The molecular structure of the title compound with atom labels and 40% probability displacement ellipsoids for non-H atoms.  The interconnection of AA dimers (a) and BB dimers (b) into corresponding chains via dissimilar C-H···O interactions.