Crystal Structure, Thermal and Fluorescence Properties of 2,2':6',2''-terpyridine-1,1',1''-triium Tetra-chlorido-nickelate(II) Chloride

The title compound, (CHN)[NiCl]Cl, comprises an Ni cation tetra-hedrally coordinated by four chloride anions, a non-coordinating chloride anion and an essentially planar terpyridinium trication (tpyH), 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) cations through an aromatic C-H⋯Cl inter-action, forming a zigzag chain extending along the 2 () screw axis. Two of the anionic Cl atoms of the [NiCl] anions form Ni-Cl⋯π inter-actions with separate pyridinium rings [Ni⋯ = 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.