Poly[[bis­{μ₂-N²,N⁶-bis­[(pyridin-3-yl)methyl]pyridine-2,6-dicarbox­amide}dichloridonickel(II)] N,N-dimethyl­formamide tetra­solvate]

In the title compound, {[NiCl₂(C₁₉H₁₇N₅O₂)₂]·4C₃H₇NO}_n, the Ni^II atom is located on an inversion centre and is in a six-coordinated octa­hedral geometry, formed by four pyridine N atoms from four N²,N⁶-bis­[(pyridin-3-yl)methyl]pyridine-2,6-dicarboxamide (BPDA) ligands occupying the equatorial plane and two chloride anions at the axial sites. The bidentate bridging BPDA ligands link the Ni^II atoms into a two-dimensional corrugated grid-like flexible layer with a (4,4)-connected topology, which consists of left- and right-handed helical chains sharing the common Ni^II atoms. Investigation of the thermal stability shows that the network is stable up to 573 K.