Dft Calculations and Spectroscopic Studies of some Ni Dimethylglyoximebased Complexes Isolated by the Hydrothermal Process

Abstract

In this paper, we report the synthesis of dimethylglyoximato-nickel complexes by the hydrothermal method. This process is rarely used for the preparation of coordination compounds. In order to identify the oxidation state of nickel within the complexes, the complexation study was conducted in two ways (with or without an oxidizing chemical agent, namely potassium persulfate). New mononuclear dimethylglyoxime–nickel complexes are isolated and thoroughly characterized by elemental analyses and commonly used spectral techniques. The EPR investigation confirms the oxidation state of nickel in all complexes. Infrared spectroscopy (IR) and nuclear magnetic resonances (¹H and ¹³C) indicate the formation and presence of new reduced forms of oximes within the complexes, namely enamine. From all these investigations, the suggested formulas for the complexes are: (Ni(C₄H₇N₂O)₂OH), named bis(3-aminobut-3-en-2-one oximato)hydrox nickel(III), noted Ca, obtained without an oxidizing chemical agent and Ni(C₄H₆N₂O)₂(OH)₂), named bis(3-aminobut-3-en-2-one oximato) dihydroxy nickel(IV), noted Cb, obtained with an oxidizing chemical agent. The experimental IR, ¹H and ¹³C NMR results and the electronic spectra (UV) are compared to those obtained theoretically by the DFT method, with the B3LYP function and the LANL2DZ basis set. The energy, structural, and electronic parameters are determined for the ligand and each complex studied. Binding energies are also theoretically evaluated for each complex.