Crystal structures, DFT calculations and biological activities of three mercury complexes from a pentadentate thioether ligand

Three mercury complexes from a symmetric pentadentate ligand 2, 6-bis (8-quinolinyl thiomethyl) pyridine (L) have been prepared by the method of diffusing of diethyl ether or diisopropyl ether. The structures of the complexes have been identified by elemental analysis (EA), infrared spectra (IR) and single-crystal diffraction, and are composed of discrete mononuclear units in complexes 1 and 2 and binuclear units in complex 3. Especially, the valence of Hg in complex 3 is reduced to − 1 in-situ during self-assembly and Hgsingle bondHg σ bond is formed, which is further evidenced by the frontier orbital and natural bond orbital (NBO) properties calculated by DFT method. The antibacterial and antifungal activities of the ligand and the three complexes were also determined, which prove foundation information for research and application in pharmaceutical chemicals.