Crystal structure, thermal and fluorescence properties of 2,2′:6′,2′′-terpyridine-1,1′,1′′-triium tetra­chlorido­nickelate(II) chloride

The title compound, (C(15)H(14)N(3))[NiCl(4)]Cl, comprises an Ni(II) cation tetra­hedrally coordinated by four chloride anions, a non-coordinating chloride anion and an essentially planar terpyridinium trication (tpyH(3) (3+)), in which the central pyridinium ring forms dihedral angles of 5.7 (2) and 6.0 (2)° with the peripheral pyridinium rings. Three inter-species N—H⋯Cl hydrogen bonds are formed with the Cl(−) anion, which also forms a link between the (tpyH(3) (3+)) cations through an aromatic C—H⋯Cl inter­action, forming a zigzag chain extending along the 2(1) (b) screw axis. Two of the anionic Cl atoms of the [NiCl(4)](2−) anions form Ni—Cl⋯π inter­actions with separate pyridinium rings [Ni⋯Cg = 3.669 (3) and 3.916 (4) Å]. In the crystal, successive undulating inorganic and organic layers are formed, extending across the (100) plane. Thermogravimetric and differential thermal analysis (TGA/DTA) indicate that the compound starts to decompose at 313 K and may be a candidate for use as a blue-light luminescent material.