Crystal structures, spectra properties and DFT calculations studies on 4-phenyl-1-(3-phenylallylidene)thiosemicarbazide and its Ni(II) complex

•The title ligand and its Ni(II) complex were synthesized and characterized.•Crystal structures of the two compounds were obtained.•DFT calculations of structure, NPA analysis and electronic spectra were performed.•Experimental structures and electronic spectra were compared with the predicted ones.•Thermodynamic properties of the two compounds were studies.

4-Phenyl-1-(3-phenylallylidene)thiosemicarbazide (HL) and its metal complex of NiL2 have been synthesized. For them, elemental analysis, IR and X-ray single crystal diffraction have been carried out. In complex NiL2, the central Ni2+ ion coordinates with two deprotonated ligands of L− and adopts a distorted square planar configuration with the Ni2+ ion being located at the inversion center. The thermal analyses result shows that complex NiL2 undergoes two decomposition processes. For the title compounds, DFT calculations of the structures and natural population analysis (NPA) have been performed at B3LYP/LANL2DZ level of theory. The predicted geometric parameters are compared with the experimental values and they are supported each other. By using TD-DFT method, electron spectra of ligand HL and complex NiL2 have been predicted, which suggest the B3LYP/LANL2DZ method can approximately simulate the electron spectra for the system presented here. The NPA results indicate that, for ligand HL, the electronic absorption spectra are mainly assigned to n–π∗ and π–π∗ electron transitions, while for the complex NiL2, the electronic transitions are mainly derived from the contribution of an intra-ligand (IL) transition, a metal-to-ligand charge transfer (MLCT) transition and a d–d transition. Based on vibrational analysis, thermodynamic properties for ligand HL and complex NiL2 at different temperatures have been obtained.

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