A New Nickel(II) Complex Derived From Bisthiocarbohydrazone: Synthesis, Characterization, Crystal Structure and Antioxidant Activity

A new complex with composition [Ni(L)(PPh3)] (PPh3 = triphenylphosphine) was obtained from the reaction of 1,5-bis(salicylidene)thiocarbohydrazone (L) with an equimolar amount of [NiCl2(PPh3)2]. The complex was identified by FT-IR, 1H NMR and UV-Vis spectroscopic methods and elemental analysis. The solid state structure of [Ni(L)(PPh3)] was established by X-ray diffraction analysis. It was determined that the complex, whose nickel center has a distorted square planar configuration, crystallizes in the monoclinic space group I2/c. Bisthiocarbohydrazone (L) binds to the nickel center through its phenolate O, azomethine N and thioenolate S atoms in a dianionic tridentate mode. The antioxidant capacity of L and Ni(II) complex was examined using the CUPRAC (cupric reducing antioxidant capacity) method. Also, the DPPH (1,1-Diphenyl-2-picrylhydrazyl) method was used to test free radical scavenging activity of the compounds. Antioxidant activity results showed that L exhibited better activity than Ni(II) complex.