Bis[1-(2,6-dimethylanilino)propane-1,2-dione dioximato]nickel(II)

# 2005 International Union of Crystallography Printed in Great Britain – all rights reserved The structure of the title complex consists of isolated [Ni(C11H14N3O2)2] units. The Ni atom is coordinated by four oxime N atoms in distorted square-planar geometry and lies on an inversion centre. The structure is stabilized by strong intramolecular N—H O and O—H O hydrogen bonds and a possible N—H intermolecular interaction.

The structure of the title complex consists of isolated [Ni(C 11 H 14 N 3 O 2 ) 2 ] units. The Ni atom is coordinated by four oxime N atoms in distorted square-planar geometry and lies on an inversion centre. The structure is stabilized by strong intramolecular N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds and a possible N-HÁ Á Á intermolecular interaction.

Comment
This work is part of our ongoing research on the synthesis and characterization of new vic-dioximes and their transition metal complexes (Zü lfikaroglu et al., 2003). Metal complexes of various glyoximate ligands have long been of importance in analytical chemistry and medicine (Chakravorty, 1974;Michael et al., 2000).
The different N-O bond lengths reflect the chemically distinct O atoms. The oxime group has an E configuration with planar O1-N2-C9-C10. The oxime OH group is adjacent to the bridging amine group in all complexes, and in (I) accepts an intraligand N-HÁ Á ÁO bond. The benzene and fivemembered chelate (NiC 2 N 2 ) rings in (I) are essentially planar, with r.m.s. deviations of only 0.0045 and 0.0159 Å .
The intramolecular inter-ligand OÁ Á ÁO separations in these compounds are all similar, lying between 2.462 (3) and 2.547 (3) Å . Such short OÁ Á ÁO separations are often associated with symmetrical OÁ Á ÁHÁ Á ÁO hydrogen bonds (Chakravorty, 1974). In (I), one of the O-bound acidic H atoms is lost from each ligand during complex formation and the remaining O-bound H atom participates in a very strong intramolecular hydrogen bond to the adjacent O atom ( Table 2). The H atom was clearly visible in a difference map and, like the other complexes noted above, the O-HÁ Á ÁO bond is not symmetrical.
Crystal data [Ni(C 11 H atoms treated by a mixture of independent and constrained refinement Table 1 Selected geometric parameters (Å , ).
The O-and N-bound H atoms were found in difference maps and were refined with distance restraints [O-H = 0.84 (2) Å and N-H = 0.86 (2) Å ] and with U iso (H) = 1.2U eq (carrier). C-bound H atoms were placed in calculated positions (C-H = 0.93-0.96 Å ) and refined as riding, with U iso (H) = 1.2 U eq (carrier) or U iso (H) = 1.5U eq (methyl carrier). The -CH 3 groups were rotated to fit the electron density.
The authors thank Ondokuz Mayıs University for financial support.   from a chloroform-ethanol mixture (2:1) gave orange rod crystals of (I).

S3. Refinement
The O-and N-bound H atoms were found in difference maps and were refined with distance restraints [O-H = 0.84 (2) Å and N-H = 0.86 (2) Å] and with U iso (H) = 1.2U eq (carrier) to yield the final values given in Table 2. C-bound H atoms were placed in calculated positions (C-H = 0.93-0.96 Å) and refined as riding with U iso (H) = 1.2 U eq (carrier) or U iso (H) = 1.5 U eq (methyl carrier). The -CH 3 groups were rotated to fit the electron density.

Figure 1
View of (I) showing 40% probability displacement ellipsoids (arbitrary spheres for the H atoms) and hydrogen bonds as

Bis[1-(2,6-dimethylanilino)propane-1,2-dione dioximato]nickel(II)
Crystal data [Ni(C 11  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.45 e Å −3 Δρ min = −0.16 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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.