Dibromidobis(4-hydroxy-1,5-dimethyl-2-phenyl-3-pyrazolone)zinc(II)

In the title compound, [ZnBr2(C11H12N2O2)2], the Zn(II) ion is coordinated by two Br atoms and two O atoms from two 4-hydroxyantipyrine molecules via the carbonyl O atoms, which act as monodentate ligands, giving rise to a distorted tetrahedral geometry. The values of the bond angles at the Zn atom are in the range 99.4 (1) to 113.2 (1)°. The presence of O—H⋯O and O—H⋯Br intramolecular hydrogen bonds can explain the difference between the two Zn—O [1.961 (3)/2.015 (3) Å] and the two Zn—Br [2.350 (1)/2.378 (1) Å] bond lengths. The crystal structure is governed by C—H⋯O, C—H⋯Br and Zn—Br⋯Cg(π-ring) interactions.

In the title compound, [ZnBr 2 (C 11 H 12 N 2 O 2 ) 2 ], the Zn(II) ion is coordinated by two Br atoms and two O atoms from two 4hydroxyantipyrine molecules via the carbonyl O atoms, which act as monodentate ligands, giving rise to a distorted tetrahedral geometry. The values of the bond angles at the Zn atom are in the range 99.4 (1) to 113.

Comment
Metals like Zn are expected to be involved in neurodegenerative diseases such as Alzheimer or Parkinson leading to neurofibrillary tangles degeneration and tau protein accumulation (Filiz et al.,2008;Tougu et al.,2008). These amyloi¨d plaques in the cortical brain are the sign of cerebral aging and associated with a neuronic a high level of metals. Much work (Melov et al., 1998) is now devoted to theses diseases since no real drug is available up to date. As researchers postulate that soft chelating drugs could interfere with free metal accumulation and neuronal collapsus, our idea was that phenazone (antipyrine), a well known antipyretic brain available drug, could become a soft chelating molecule upon hydroxylation in the 4-hydroxy derivative. For this reason and our knowledge in metal amide complexes, (Bekaert et al., 2007;Lemoine et al., 2007) we have prepared a new cristalline complex including Zn and 4-hydroxy-1,5-dimethyl-2-phenyl-3-pyrazolone (4-hydroxyantipyrine) which is of considerable interest as a antipyrine primary metabolite and which is the object of many biological studies the latter years, by example in the evaluation of the influence of diabete mellitus on antipyrine metabolism (Matzke et al., 2000).
The hydroxyamide structure which is close to lactamide let us to test it as a metal pinch. Following our work concerning lactamide and zinc(II) complex (Bekaert et al., 2003), we now report a new zinc complex with 4-hydroxyantipyrine.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 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.