catena-Poly[[bis(nitrato-κ2 O,O′)cobalt(II)]-μ-4,4′-bis(pyrazol-1-ylmethyl)biphenyl-κ2 N 2:N 2′]

In the title compound, [Co(NO3)2(C20H18N4)]n, the CoII atom lies on a crystallographic twofold axis and the coordination geometry can be considered as a slightly distorted tetrahedron defined by two O atoms from two nitrate groups and two N atoms from two ligand molecules. A distorted octahedron may be assumed when two of the symmetry-related nitrate O atoms with Co—O distances of 2.3449 (19) Å are added to the coordination environment. Another twofold axis, passing through the middle of the biphenyl bonds, is observed in the crystal structure. A chain is built up by the ligands linking the CoII ions along [101].

In the title compound, [Co(NO 3 ) 2 (C 20 H 18 N 4 )] n , the Co II atom lies on a crystallographic twofold axis and the coordination geometry can be considered as a slightly distorted tetrahedron defined by two O atoms from two nitrate groups and two N atoms from two ligand molecules. A distorted octahedron may be assumed when two of the symmetry-related nitrate O atoms with Co-O distances of 2.3449 (19) Å are added to the coordination environment. Another twofold axis, passing through the middle of the biphenyl bonds, is observed in the crystal structure. A chain is built up by the ligands linking the Co II ions along [101].

Related literature
For a related polymeric bis(pyrazole) dinitratocobalt(II) structure, see: Chen et al. (1997). For the isotypic Zn structure, see: Wang et al. (2010). For the synthesis and structure of a three-dimensional polymeric Zn(II) network compound, see: Zhu et al. (2002).

Comment
The structures of the metal derivative 1,4-bis(pyrazole) benzene are known for zinc and cobalt (Chen et al., 1997). In order to enrich the research of this kinds of ligand, a new ligand 4,4'-bis(pyrazole) biphenyl with longer spacer was synthesized.
In here, we report the strucuture of the title compound, which is a isomorphic compound of our previous report (Wang et al., 2010).
The central Co atom lies on a crystallographic twofold axis and the coordination geometry can be considered as a slightly distorted tetrahedron defined by two O atoms from two nitrate groups and two N atoms from two ligand molecules. A distorted octahedron may be assumed when two of the C 2 related nitrate oxygen atoms with Co-O distances of 2.345 (2) Å are added to the coordination environment. Another twofold axis, passing through the middle of the biphenyl bonds, is observed in the crystal structure ( Figure 1, Table 1).
A one dimensional chain is built up by the ligands linking the Co II ions along the [1 0 1] direction ( Figure 2).