trans-Dimethanolbis(1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionato)zinc(II)

The title compound, [Zn(C8H10F3O2)2(CH4O)2], is a dimethanol coordinated zinc complex with the acetyl acetonate derivative 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate. The bis-β-diketonate complex, which is isostructural with its Co analogue, is located on a crystallographic inversion center. The complex is octahedral with basically no distortion, and the methanol molecules are in trans positions with respect to one another. The planes of the β-diketonate and the ZnO4 unit are tilted by 18.64 (10)° against each other. O—H⋯O hydrogen bonds between the methanol hydroxyl groups and neighboring diketonate O atoms create chains running along [100].

The title compound, [Zn(C 8 H 10 F 3 O 2 ) 2 (CH 4 O) 2 ], is a dimethanol coordinated zinc complex with the acetyl acetonate derivative 1,1,1-trifluoro-5,5-dimethylhexane-2,4dionate. The bis--diketonate complex, which is isostructural with its Co analogue, is located on a crystallographic inversion center. The complex is octahedral with basically no distortion, and the methanol molecules are in trans positions with respect to one another. The planes of the -diketonate and the ZnO 4 unit are tilted by 18.64 (10) against each other. O-HÁ Á ÁO hydrogen bonds between the methanol hydroxyl groups and neighboring diketonate O atoms create chains running along [100].

Related literature
For information regarding the synthesis of various metal -diketonates refer to Watson & Lin (1966). For mass spectrometry related articles see Lerach & Leskiw (2008) and Schildcrout (1976). For a variety of applications and properties of metal -diketonate complexes refer to Burtoloso (2005), Katok et al. (2006) and Condorelli et al. (2007). Lerach et al. (2007) report the structure of the Co analogue of the title compound.
The title compound, [Zn(C 8 H 10 F 3 O 2 ) 2 (CH 3 OH) 2 ], which is isostructural with its Co analogue (Lerach et al., 2007) is a dimethanol coordinate of a zinc complex with the ligand 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dionate, an acetyl acetonate derivative with each a tert-butyl and a trifluoromethyl substituent. A thermal ellipsoid plot of the molecule is shown in Fig.   1. The bis-β-diketonate complex is located on a crystallographic inversion center with the two methanol molecules in trans position to each other. The coordination environment of the central zinc cation is octahedral with only a very slight distortion: angles around the Zn atom deviate from 90° by 0.36 (8)° or less, and Zn-O distances are 2.054 (2) and 2.040 (2) Å for the zinc β-diketonate bonds and 2.161 (2) Å towards the methanol molecules. The mean planes of the diketonate ligands, defined by the atoms O1, O2 and C1 to C5, and that of the ZnO 4 unit are tilted against each other by an angle of 18.64 (10)°, which is virtually identical to the vaule of 17.41 (7)° observed in the structure of the Co analogue of the title compound.
Packing of the molecules within the structure is assisted by hydrogen bonds between the methanol hydroxyl groups and diketonate oxygen atoms of neighboring molecules (Table 1). The O-H···O interactions create hydrogen bonded chains that stretch along the a-axis of the structure.

Experimental
The synthesis of the title compound was adapted from Watson & Lin (1966). 0.80 ml (5.0 mmol) of the ligand were added to a stirring solution of 0.22 g of ZnCl 2 (1.6 m mol) and 50 ml of de-inoized water. Diluted 1:1 (v/v) NH 4 OH was added dropwise to the mixture until no more visible precipitate formed. The solution was stirred for another hour at room temperature, and the precipitate was isolated by vacuum filtration. The desired product was re-crystallized by overnight evaporation of a concentrated methanolic solution.

Refinement
The hydroxyl H atom was located in a difference density Fourier map and the O-H distance was restrained to 0.84 (2) Å.
All other H atoms were placed in calculated positions with C-H distances of 0.98 (methyl) and 0.95 Å (CH). The methyl and hydroxyl H's were refined with an isotropic displacement parameter U iso of 1.5 times U eq of the adjacent carbon or supplementary materials sup-2 oxygen atom, and the C-H hydrogen atom with U iso = 1.2 U eq (C). Methyl hydrogen atoms were allowed to rotate to best fit the experimental electron density. Fig. 1. ORTEP representation of the asymmetric unit of the title compound (50% probability displacement ellipsoids). H atoms are shown as circles of arbitrary radii.

Special details
Geometry. All e.s. 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.