{2,2′-[o-Phenylenebis(nitrilomethylidyne)]diphenolato}dipyridinecobalt(III) perchlorate

The title compound, [Co(C20H14N2O2)(C5H5N)2]ClO4 or [Co(salophen)(py)2]ClO4, where salophen is o-phenylenebis(nitrilomethylidyne)]diphenolate and py is pyridine, contains a six-coordinate mononuclear cobalt(III) atom. The two phenolic O atoms and the two imine N atoms are located in cis positions. There are two pyridine molecules attached to the metal atom, filling the axial sites with a mutually perpendicular disposition of the pyridine planes [86.11 (5)°]. The Co complexes are stacked in layers parallel to (100). Coherence of the structure is provided by a variety of C—H⋯O interactions between the complexes and the perchlorate counter anion.

The title compound, [Co(C 20 H 14 N 2 O 2 )(C 5 H 5 N) 2 ]ClO 4 or [Co(salophen)(py) 2 ]ClO 4 , where salophen is o-phenylenebis(nitrilomethylidyne)]diphenolate and py is pyridine, contains a six-coordinate mononuclear cobalt(III) atom. The two phenolic O atoms and the two imine N atoms are located in cis positions. There are two pyridine molecules attached to the metal atom, filling the axial sites with a mutually perpendicular disposition of the pyridine planes [86.11 (5) ]. The Co complexes are stacked in layers parallel to (100). Coherence of the structure is provided by a variety of C-HÁ Á ÁO interactions between the complexes and the perchlorate counter anion.
Partial support of this work by the Isfahan University of Technology Research Council is gratefully acknowledged.

S1. Comment
Transition metal Schiff-base complexes with the tetradentate ligand configuration N 2 O 2 have been extensively studied (Yamada et al., 1999;Schenk et al., 2007). Some of these complexes have interesting applications, e.g., their ability to reversibly bind oxygen, and their use in catalysis for oxygenation and oxidation reactions of organic compounds (Nishinaga et al., 1980;Park et al., 1998;Speiser et al., 1995). Among these metal complexes, cobalt(III) Schiff base complexes with two amines in axial positions have especially attracted interest due to their ability as antimicrobial agents (Kumar et al., 2009;Miodragović et al., 2006;Mishra et al., 2008). The synthesis and reactivity of these complexes have also been playing an important part in the development of coordination chemistry. In this context, we herein report the synthesis and structure of the title compound, [Co(salophen)(py) 2 ]ClO 4 , (I), and make a brief comparison with reported structures.
As illustrated in Fig et al., 2007] share a similar strong distortion, each having one phenolate moiety distinctly bent off from the least-squares plane of the remaining salophen ligand atoms, as is schematically shown by the chemical diagram of (I) and by the fact that in (I) the angle between the two least squares planes of phenolate O(1)-C(1)-C(2)-C(3)-C(4)-C(5)-C(6) and the rest of the salophen ligand is 25.27 (6)°. The two complexes differ however in the mutual orientations of the pyridine/picoline ligands -nearly perpendicular in (I) (interplanar angle 86.11 (5)°), but almost parallel in the picoline compound.

S2. Experimental
To a stirring solution of Co(CH 3 COO) 2 .4H 2 O (0.125 g, 0.5 mmol) in methanol (25 ml) was added an equimolar of salophen (0.158 g, 0.5 mmol). The red solution turned brown immediately upon the formation of [Co II (salophen)] complex. To this solution was added 4 mmol of pyridine, and air was bubbled through the reaction mixture for about 3 h.
To the resulting brown solution was then added 0.5 mmol (0.0615 g) of NaClO 4 and stirred for 5 minutes. Brown crystals of the complex suitable for X-ray crystallography were obtained after three days by slow evaporation of the methanol.
The crystals were filtered off and washed with a small amount of cold methanol and dried under vacuum. Yield: 80%.

S3. Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.95Å and U iso (H) = 1.2 U eq .

Figure 1
The ORTEP drawing of (I), with the atom labeling scheme. Displacement ellipsoids are drawn at the 50% probability level.  The crystal packing of (I), viewed along the b axis.

{2,2′-[o-Phenylenebis(nitrilomethylidyne)]diphenolato}dipyridinecobalt(III) perchlorate
Crystal data [Co(C 20   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.