Novel copper(II) and nickel(II) coordination complexes of 2,4-pentanedione bis-thiosemicarbazone: Synthesis, structural characterization, computational studies, and magnetic properties

The reaction of the proligand thiosemicarbazido 2-pyrazoline (H2L2), derived from 2,4-pentanedione bis-thiosemicarbazone (H2L1) with Cu(II) and Ni(II) salts, under aerobic conditions, yielded the mononuclear title complexes [M((LO)-O-1)]. The open form of the ligand, H2L1, is oxidized at the central CH2 of the backbone and doubly deprotonated. The obtained complexes were characterized by using single crystal X-ray diffraction, FT-IR and UV-Vis spectroscopic techniques. The structures of the title complexes were determined respectively in monoclinic and triclinic symmetry, where the copper complex [Cu((LO)-O-1)] and nickel complex [Ni((LO)-O-1)] crystallize in the centrosymmetric space groups C2/c and P (1) over bar, respectively. The asymmetric unit is formed of M-II atom occupying a general position, linked by two sulfur and two nitrogen atoms, to form (MS2N2)-S-II square plane environment in both complexes. The crystal structure stabilization of both complexes is ensured by weak interactions hydrogen bonds D-H center dot center dot center dot A with (D = N, C and A = N, O, Sand / or C). This has been confirmed by the three dimensional Hirshfeld surface analysis and the two dimensional fingerprint plots that highlight the dominance of H center dot center dot center dot H, S center dot center dot center dot H/H center dot center dot center dot S and H center dot center dot center dot N/N center dot center dot center dot H intermolecular interactions. The magnetic study revealed that the magnetic chains of Cu and Ni transition metal atoms in square plane environment show two different magnetic interactions in both investigated complexes, with linear and undulating (on zig-zag) metallic chains in Cu and Ni complexes, with antiferromagnetic behaviour for the first complex and ferrimagnetic for the second one.