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

In the title compound, [Al(C5H6ClO2)3], the AlIII cation is situated on a twofold rotation axis and is coordinated by six O atoms from three 3-chloropentane-2,4-dionate ligands in an octahedral environment. Al—O bond lengths are in the range 1.8741 (14)–1.8772 (14) Å. In the crystal, molecules are linked via C—H⋯Cl contacts.

In the title compound, [Al(C 5 H 6 ClO 2 ) 3 ], the Al 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 an octahedral environment. Al-O bond lengths are in the range 1.8741 (14)-1.8772 (14) Å . In the crystal, molecules are linked via C-HÁ Á ÁCl contacts.

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). β-Diketonate compounds of aluminium have received great attention due to the promise of the construction of cages (Vreshch et al., 2004;Wu & Wang, 2009). Besides that, aluminium β-diketonates and malonates can be good precursors in metal-organic chemical vapour deposition (MOCVD) (Bray et al., 2007;Garibay et al., 2009;Lichtenberger et al., 2010).
In the title molecule ( Fig. 1), the aluminium(III) cation is situated on a twofold axis, and is surrounded by six O atoms from three 3-chloropentane-2,4-dionate ligands in a octahedral environment. The geometry around aluminium is close to the orthogonallity as can be seen from the angles. The Al-O bond lengths are in the range 1.8741 (14)-1.8772 (14) Å and are similar as for example in Al(acac) 3 (Hon & Pfluger, 1973). The displacement of the metal atom is best described by a bending of a chelate ligand about the "bite" atoms. The angles between the O-Al-O and the ligand chelate mean planes are 0.38° and 1.72°. For comparison these values are 0.78° and 12.68° in the isostructural iron(III) compound (Perdih, 2012). A 1-D framework is achieved due to intermolecular C6-H6A···Cl1 (-x + 1/2, -y + 1/2, -z) contacts ( Fig.   2).

Experimental
To a clear solution of Al 2 (SO 4 ) 3 . 18H 2 O (1 mmol, 0.67 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 light pink product was filtrated, washed with water (20 ml), and subsequently air-dried. Yield: 0.60 g, 70%. 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).    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  (17)