Unprecedented platinum(II) coordination compound of sterically hindered 3,3′-bis(NH-benzimidazol-2-yl)-2,2′-bipyridine ligand

Abstract

The synthesis, spectroscopic characterization, single-crystal X-ray diffraction (SCXD) analysis, and Density Functional Theory (DFT) and time-dependent DFT (TD-DFT) studies of the coordination compound of cis-dichloroplatinum(II) with a sterically hindered N4-donor ligand, 3,3′-bis(NH-benzimidazol-2-yl)-2,2′-bipyridine (L), [Pt(L)Cl2]⋅DMSO (1) (DMSO = dimethyl sulfoxide) are reported. The Pt(II) ion adopts a slightly distorted square-planar geometry in which L coordinates in a bidentate fashion to the metal center through N atom of benzimidazole (bim) and N atom of pyridine (py) to form a seven-membered ring. The molecular units in the lattice are held together in a head to tail fashion as a dimer through intermolecular hydrogen bonding between the uncoordinated bim and py rings in the molecule through N H⋅⋅⋅N hydrogen bonds with the R22 (14) graph-set motif. The lattice DMSO solvent molecule significantly stabilizes the structure through N H⋅⋅⋅O hydrogen bond with the coordinated bim in the structure. Hirshfeld surface analysis also confirmed the hydrogen bond interactions in the crystal. DFT and TD-DFT results show that optimized geometry and UV-vis absorption spectra are consistent with the experimental results. Natural bond orbital (NBO) properties show that the hydrogen bond stability between the two monomers attributes with large stabilization energy values.