Dichlorotetrakis[3-(4-pyridyl)-1H-pyrazole]cobalt(II) acetonitrile tetrasolvate: an infinite hydrogen-bonded network, in an instant.

Reaction of 3-(4-pyridyl)pyrazole (4pypz) with cobalt(II) chloride in acetonitrile affords the title complex, [CoCl(2)(C(8)H(7)N(3))(4)].4CH(3)CN, within seconds of addition, as purple X-ray quality crystals. The molecule has C4 symmetry. The metal ion exhibits a trans-N(4)Cl(2) octahedral geometry, with the four 3-(4-pyridyl)-1H-pyrazole ligands coordinating through their pyridyl N-atom donors; one coordinated chloride ion forms hydrogen bonds with the pyrazole rings from four separate units. This configuration creates an infinite three-dimensional coordination network containing channels that are filled with acetonitrile solvent molecules.