Crystal exploring, Hirshfeld surface analysis, and properties of 4′‐(furan‐2‐yl)‐2,2′:6′,2″‐terpyridine complexes of nickel (II): New precursors for the synthesis of nanoparticles

Abstract

A series of mono‐ and bis‐terpyridine complexes of nickel (II) based on the 4′‐(furan‐2‐yl)‐2,2′:6′,2″‐terpyridine (ftpy) have been synthesized and structurally characterized using elemental analysis, infrared spectroscopy, and single crystal X‐ray diffraction. The reaction of NiCl2•6H2O with ftpy has been resulted in the formation of new bis‐terpyridine complex [Ni (ftpy)2](PF6)•2H2O (1). The new complex [Ni (ftpy)2](PF6)2 (2), obtained during the crystallization of 1 in methanol, was characterized using X‐ray crystallography, which shows that six nitrogen atoms from terpyridine ligands occupy the coordination sites around the Ni (II) in a distorted octahedral geometry. On the other hand, the reaction of NiCl2•6H2O with ftpy in a 1:2 or 1:1 mole ratio in methanol in the presence of KSCN affords two new thiocyanato complexes [Ni (ftpy)2](SCN)2•2H2O (3) and [Ni (ftpy)(NCS)2(H2O)]•2H2O (4), respectively. The crystal structure of 3 reveals that nickel (II) is hexa‐coordinated in a distorted octahedral geometry NiN6 involving six atoms of two ftpy ligand; the ftpy ligands are perpendicular to each other. The new complex [Ni (ftpy)(NCS)2(DMSO)]•DMSO (5) is obtained during the crystallization of 4 in DMSO. The crystal structure of 5 reveals that the nickel (II) is hexa‐coordinated by three nitrogen atoms of ftpy, two NCS−, a DMSO in a slightly distorted octahedral geometry. The X–H (XH, C, N, O) bond interactions control the arrangement of the supramolecular 3D framework. Hirshfeld surface analyses and two‐dimensional fingerprint plot reveal that the main interactions are H–H contacts for 2, 3, and 5, which comprise 34.1%, 37.2%, and 34.6%, respectively. Thermal decomposition of the coordination complexes led to the formation of Ni, NiO, and Ni2P2O7 nanoparticles (NPs). The resulting NPs were fully characterized by powder XRD, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and energy‐dispersive X‐ray spectroscopy (EDX). The formation of these NPs indicates the role of the precursor complexes and counterion. Our results indicate that the NPs with the smaller size could be obtained at calcination temperature of 600 °C. Thermal and luminescent properties of complexes have been discussed in detail.