Bis{2-[(2-pyridyl)iminomethyl]phenolato}copper(II)

In the title compound, [Cu(C12H9N2O)2], the CuII atom lies on a crystallographic inversion center and has a nearly square-planar geometry. The CuII center coordinates to the phenolic O and azomethine N atoms of the two symmetry-related 2-[(2-pyridyl)iminomethyl]phenolate ligands. The pyridyl N atoms do not coordinate to the CuII atom but participate in intramolecular C—H⋯N hydrogen bonding. π–π stacking between the benzene rings and between the pyridyl rings [centroid–centroid distances 3.8142 (5) and 3.8142 (5) Å, respectively] links the molecules into a chain propagating parallel to [100].

In the title compound, [Cu(C 12 H 9 N 2 O) 2 ], the Cu II atom lies on a crystallographic inversion center and has a nearly squareplanar geometry. The Cu II center coordinates to the phenolic O and azomethine N atoms of the two symmetry-related 2- [(2pyridyl)iminomethyl]phenolate ligands. The pyridyl N atoms do not coordinate to the Cu II atom but participate in intramolecular C-HÁ Á ÁN hydrogen bonding.stacking between the benzene rings and between the pyridyl rings [centroid-centroid distances 3.8142 (5) and 3.8142 (5) Å , respectively] links the molecules into a chain propagating parallel to [100].

Related literature
For the preparation of the title compound by an electrochemical method, see: Castineiras et al. (1989), and by a solution method, see: Parashar et al. (1988). For the crystal structures of related compounds, see: Castineiras et al. (1989).
has been prepared using an electrochemical method by Castineiras et al. (1989) starting from N-salicylidene 2-aminopyridine and copper. Parashar et al. (1988) reported that refluxing a mixture of Cu(OAc) 2 (OAc = acetato) and N-salicylidene 2-aminopyridine in a 1:2 molar ratio resulted in a green complex having the same formula but with an octahedral geometry deduced from spectroscopic properties. We have found that a simple method of solution diffusion produces the brown title compound.
As shown in Fig. 1, the copper atom lies on a crystallographic inversion center and has a square planar geometry. The copper center coordinates to the phenolic oxygen and the azomethine nitrogen atoms of the two symmetry related groups. The pyridyl nitrogen atoms do not coordinate to the copper. The Cu-O bond lengths are 1.9212 (17) Å, and the Cu-N bond lengths are 2.0216 (19) Å, respectively, all similar to those reported in the related structures (Castineiras et al., 1989).

Refinement
All H-atoms were positioned geometrically and refined using a riding model with d(C-H) = 0.93 Å, U iso =1.2U eq (C). Fig. 1. The molecular structure, with atom labels and 25% probability thermal ellipsoids.