Polymorphism of Palladium(II) Complexes : Crystal Structure Determination, Luminescence Properties, Hirshfeld Surface Analyses and DFT/TD-DFT Studies

چکیده مقاله

Two luminescent polymorphs based on a new Pd(II) complex [Pd(mtzt)₂(en)] (mtzt=1-methyl-1H-1,2,3,4-tetrazole-5-thiol and en=ethylenediamine) have been synthesized and characterized by FTIR, UV/Vis, elemental analysis,¹HNMR and single-crystal X-ray diffraction analysis. The X-ray structural analysis indicated that in the structures of these polymorphs Pd(II) cation is four-coordinated in a distorted square planer configuration by two tetrazole rings in the cis-positions, two nitrogen atoms of chelated ethylenediamine ligand. The dihedral angles between the planes of the tetrazole rings of polymorphs (1) and (2) are 72.01 and 77.70°, respectively. Moreover, in these polymorphs, intermolecular interactions C−H…N, C−H…S, and N−H…N hydrogen bonds, are effective in the stabilization of the crystal structures. The present study reports a detailed analysis of Hirshfeld surfaces, facilitating a comparison of intermolecular interactions in the supramolecular structure. The geometries of polymorphs (1) and (2) are optimized with B3LYP−D3/TZVP method, and analyzed with natural bond orbital (NBO), then their UV/Vis spectra are calculated with time-dependent density functional theory (TD-DFT) method. The IR spectroscopy was performed using VEDA4 software and compared with the experimental values. Quantum chemical parameters are: such as E_HOMO, E_LUMO, energy gap, chemical hardness (η), and dipole moment (μ), and the frontier molecular orbital properties. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim