Interestingly, a modest ferromagnetic coupling (588 cm –1) is predicted between two spin- 1/ 2 Cu 2+ ions present in the Cu(DMG) 2 dimer. In dimers, Ni(DMG) 2 is found to be 6 kcal mol –1 more stable than Cu(DMG) 2 due to a greater extent of dispersive interactions. In contrast, a relatively larger reaction enthalpy for Cu(DMG) 2 formation from chemically relevant species is found than that of Ni(DMG) 2 because of the greater binding enthalpy of 2+ than that of 2+.
Stronger H-bonding leads to greater stability of Ni(DMG) 2 with respect to isolated ions (M 2+ and DMG –) compared to Cu(DMG) 2. Ni(DMG) 2 results are thoroughly compared with Cu(DMG) 2 and also against available experimental data. Using range-separated hybrid functional augmented with dispersion corrections within density functional theory (DFT) and time-dependent DFT, we present a detailed and comprehensive study on structural, electronic, and spectral (both IR and UV–vis) properties of M(DMG) 2 complexes.
Electronic and spectral properties of metal-DMG complexes are highly dependent on the nature of metal ions. Dimethylglyoxime (DMG) usually forms thermodynamically stable chelating complexes with selective divalent transition-metal ions.
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