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

Abstract

The title compound, (C15H14N3)[NiCl4]Cl, comprises an NiII cation tetrahedrally coordinated by four chloride anions, a non-coordinating chloride anion and an essentially planar terpyridinium trication (tpyH33+), 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 (tpyH33+) cations through an aromatic C—H...Cl interaction, forming a zigzag chain extending along the 21 (b) screw axis. Two of the anionic Cl atoms of the [NiCl4]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.

Keywords

• crystal structure
• nickel(II) complex
• terpyridinium cation
• protonation
• hydrogen bonds
• fluorescence