(E)-3-Ferrocenyl-1-(2-hydroxyphenyl)-prop-2-en-1-one

The molecular structure of the title compound, [Fe(C5H5)(C14H11O2)] consists of a ferrocenyl and 2-hydroxyphenyl group linked through the prop-2-en-1-one spacer and is stabilized by an intramolecular O—H⋯O hydrogen bond between the hydroxyl and the carbonyl groups.

The molecular structure of the title compound, [Fe(C 5 H 5 )-(C 14 H 11 O 2 )] consists of a ferrocenyl and 2-hydroxyphenyl group linked through the prop-2-en-1-one spacer and is stabilized by an intramolecular O-HÁ Á ÁO hydrogen bond between the hydroxyl and the carbonyl groups.

Comment
Chalcones are a family of aromatic ketones bearing two aromatic groups bridged together trough a central prop-2-en-1-one core. They have a wide range of applications covering from materials with various biological activities (Xiang et al., 2006;Wu et al., 2002Wu et al., , 2006Liu et al., 2001;Zsoldos-Mady et al., 2006) to non-linear optics (Shettigar et al., 2006), including also electroactive fluorescent materials (Belavaux-Nicot et al., (2005). Ferrocene containing chalcones are also useful precursors for the synthesis of more complex heterocyclic metallocene derivatives (Kudar et al., (2005). Typically this kind of precursors are prepared trough a Claisen Shmidt condensation, reacting a ketone or an aldehyde with the appropriated ferrocene substituted aldehyde or ketone depending on the position were the ferrocenyl substituent is required.
For the case of 1-(2'-hydroxyphenyl)-substituted prop-2-en-1-ones (as the title compound) the presence of an intense H-bonding has been previously described (Escobar et al., 2008) this structural characteristic has been recognized to play a key role in its biological activity (Rao et al., (2004).
The molecular structure of the title compound is composed by the ferrocenyl moiety and the 2'-hydroxyphenyl group joined by the organic prop-2-en-1-one spacer.
The dihedral angle between the two aromatic rings joined by the conjugated organic spacer is 12.01 (9)°. The distances between the C 5 H 5 -and C 5 H 4 -ring centroids to the iron atom are 1.653 (1)Å and 1.648 (1)Å, respectively. Both cyclopentadienyl rings of the ferrocenyl group are coplanar with a dihedral angle 1.6 (1)°. These metrical parameters are typical of the η 5 ···Fe···η 5 coordination of the ferrocenyl moiety.
The main feature of the structure is an intramolecular hydrogen bond O-H···O between the hydroxyl and the carbonyl group forming a six-membered ring helping the molecular stabilization, this characteristic has been previously observed in other 2'-hydroxy chalcones (Escobar et al., 2008). This intramolecular bond leads the carbonyl group to display an S-cisconfiguration in relation to the double bond. The double bond distance C═C is 1.325 (3)Å and exhibits a cis-conformation.
Finally, no intermolecular hydrogen bonds are observed in the crystalline packing of title compound.

Experimental
The title compound was prepared as follows: a solution of potassium hydroxide (2 g in 30 ml methanol) was added to a mixture of ferrocenecarboxaldehyde (0.6 g 4.4 mmol) and 2-hydroxyacetophenone (0.94 g 4.4 mmol). The mixture was allowed to react for three days under continuous stirring. Then, methanol was evaporated in a rotatory evaporator and the crude reaction mixture was submitted to column chromatography (silica gel 60, Ethyl acetate: Hexane = 1: 20 v/v).

Refinement
The hydrogen atoms positions were calculated after each cycle of refinement with using a riding model with C-H distances in the range 0.93Å and 0.98Å. The U iso (H) values were set equal to 1.2U eq (C). The exception were the hydroxyl hydrogen atom which were located in the Fourier and then refined with the O-H distance constrained to be 0.82Å and the U eq free to refine.

Special details
Experimental. The data collection nominally covered a full sphere of reciprocal space by a combination of 5 sets of ω-scans each set at different φ-and/or 2θ-angles and each scan (10.00 s exposure) covering -0.300° in ω. The crystal to detector distance was 6.275 cm.
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq