Crystal structure of the salt bis-(tri-ethano-lamine-κ(3) N,O,O')cobalt(II) bis-[2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetate]

Crystal Structure and Hirshfeld Surface Analysis of Bis(Triethanolamine)Nickel(II) Dinitrate Complex and a Revelation of Its Characteristics via Spectroscopic, Electrochemical and DFT Studies Towards a Promising Precursor for Metal Oxides Synthesis

Metal complexes with chelating ligands are known as promising precursors for the synthesis of targeted metal oxides via thermal decomposition pathways. Triethanolamine (TEA) is a versatile ligand possessing a variety of coordination modes to metal ions. Understanding the crystal structure is beneficial for the rational design of the metal complex precursors. Herein, a bis(triethanolamine)nickel (II) dinitrate (named as Ni-TEA) crystal was synthesized and thoroughly investigated. X-ray crystallography revealed that Ni(II) ions adopt a distorted octahedral geometry surrounded by two neutral TEA ligands via two N and four O coordinates. Hirshfeld surface analysis indicated the major contribution of the intermolecular hydrogen-bonding between —OH groups of TEA in the crystal packing. Moreover, several O–H stretching peaks in Fourier transformed infrared spectroscopy (FTIR) spectra emphasizes the various chemical environments of —OH groups due to the formation of the hydrogen-bonding framework. The Density-functional theory (DFT) calculation revealed the electronic properties of the crystal. Furthermore, the Ni-TEA complex is presumably useful for metal oxide synthesis via thermal decomposition at a moderate temperature (380 °C). Cyclic voltammetry indicated the possible oxidative reaction of the Ni-TEA complex at a lower potential than nickel(II) nitrate and TEA ligand, highlighting its promising utility for the synthesis of mixed valence oxides such as spinel structures.

Crystal structure of the salt bis-(tri-ethano-lamine-κ(4) N,O,O',O'')cadmium bis[2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetate]

The reaction of 2-(2-oxo-2,3-di-hydro-1,3-benzo-thia-zol-3-yl)acetic acid (NBTA) and tri-ethano-lamine (TEA) with Cd(CH3OO)2 resulted in the formation of the title salt, [Cd(C6H15NO3)2](C9H6NO3S)2. In its crystal structure, the complex cation [Cd(TEA)2](2+) and two independent NBTA(-) units with essentially similar geometries and conformations are present. In the complex cation, each TEA mol-ecule behaves as an N,O,O',O''-tetra-dentate ligand, giving rise to an eight-coordinate Cd(II) ion with a bicapped trigonal-prismatic configuration. All ethanol groups of each TEA mol-ecule form three five-membered chelate rings around the Cd(II) ion. The Cd-O and Cd-N distances are in the ranges 2.392 (2)-2.478 (2) and 2.465 (2)-2.475 (3) Å, respectively. O-H⋯O hydrogen bonds between the TEA hy-droxy groups and carboxyl-ate O atoms connect cationic and anionic moieties into chains parallel to [110]. Each NBTA(-) anion is additionally linked to a symmetry-related anion through π-π stacking inter-actions between the benzene and thia-zoline rings [minimum centroid-to-centroid separation = 3.604 (2) Å]. Together with additional C-H⋯O inter-actions, these establish a double-layer polymeric network parallel to (001).