Tris(3-chloropentane-2,4-dionato-κ2 O,O′)iron(III)

In the title compound, [Fe(C5H6ClO2)3], the FeIII cation is situated on a twofold rotation axis and is coordinated by six O atoms from three 3-chloropentane-2,4-dionate ligands in a slightly distorted octahedral environment. Fe—O bond lengths are in the range 1.9818 (18)–1.9957 (18) Å. The trans O—Fe—O angles are 169.06 (13) and 171.54 (8)°, whereas the corresponding cis angles are in the range 84.81 (10)–100.68 (12)°. In the crystal, molecules are linked via C—H⋯Cl interactions.

In the title compound, [Fe(C 5 H 6 ClO 2 ) 3 ], the Fe III cation is situated on a twofold rotation axis and is coordinated by six O atoms from three 3-chloropentane-2,4-dionate ligands in a slightly distorted octahedral environment. Fe-O bond lengths are in the range 1.9818 (18)

Franc Perdih
Comment β-Diketonates have been proven to be versatile ligands for various metal ions. They can be easily derivatized, thus modifying the electronic and steric nature of these ligands to design suitable structure/function relationships (Bray et al., 2007;Garibay et al., 2009;Perdih (2011). Metal-organic frameworks are considered as promising materials for many applications mostly due to interesting porosity properties. Besides the potential applications as gas storage other applications such as molecular sensing, ion exchange, catalysis, optics and magnetism have received considerable attention (Bray et al., 2007;Garibay et al., 2009). Particularly interesting is the metal-ligand coordination with applications in organic synthesis, where iron β-diketonate compounds showed great applicability. Reasons for this are the natural abundance of this metal and also it's biocompatibility, both of which are essential for the development of sustainable chemical catalysis (Schröder et al., 2011).

Experimental
To a clear solution of FeCl 3 . H 2 O (2 mmol, 0.54 g) in water (15 ml) a solution of 3-chloropentane-2,4-dione (6 mmol, 0.81 g) in methanol (5 ml) was added while stirring. Afterwards 1 M NaOH (6 ml) was slowly added and the resulting solution was stirred at 70°C for 15 minutes. After cooling to room temperature the deep red product was filtrated, washed with water (20 ml), and subsequently air-dried. Yield: 0.65 g, 71%. Crystals suitable for X-ray analysis were obtained by recrystallization from ethanol.

Refinement
All H atoms were initially located in a difference Fourier maps and were subsequently treated as riding atoms in geometrically idealized positions, with C-H = 0.96 Å, and with U iso (H) = 1.5U eq (C). To improve the refinement results, two reflections with too high value of δ(F 2 )/e.s.d. and with F o 2 < F c 2 were deleted from the refinement.

Special details
Experimental. 192 frames in 5 sets of ω scans. Rotation/frame = 2.0 °. Crystal-detector distance = 25.00 mm. Measuring time = 60 s/°. 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 cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. 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 > 2σ(F 2 ) is used only for calculating R-factors(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