Syntheses, Crystal Structures And Characterization Of The Complexes Of 2,5-disubstituted-1,3,4-oxadiazole

1,3,4-Oxadiazole are important heterocyclic compounds,some of their derivatives have antineoplastic,antiviral and bactericidal activities,and widely used in the fields of pesticides,medicine and chemical materials.In order to study the 1,3,4-oxadiazole transition metal complexes,we synthesized nine novel 2,5-disubstituted-1,3,4-oxadiazole compounds,and the crystal structures and properties of the complexes were investigated.The works in this paper are as follows.1.Nine novel compounds of 2,5-disubstituted-1,3,4-oxadiazole were synthesized,and the ultraviolet and fluorescence spectra of the 2-substituted-5-?2-pyridyl?-1,3,4-oxadiazole compounds were determined.2.Seven cadmium???complexes were prepared from the 2-substituted-5-?2-pyridyl?-1,3,4-oxadiazole compounds,and their single crystal structures were determined.The complex of[Cd₂L₂??-SCN?₄]_n is a double-bridged cadmium???polymeric complex bridged by two thiocyanate ions,and the central Cd1???atoms have distorted octahedral geometries with CdN₄S₂.The complex of[Cd₂L₂??-Cl?₄]_n is a double-bridged cadmium???polymeric complex bridged by two chloride ions,and the central Cd1???atoms have distorted octahedral geometries?CdN₂Cl₄?.The complex of[Cd₂L'₂??-Cl?₂Cl₂?H₂O?₂]is a double-bridged binuclear cadmium???complex bridged by two chloride atoms,and the central Cd1???atoms have distorted octahedral geometries?CdCl₃N₂O?.The complexes of[CdL₂¹Cl₂]and[CdL₂²Cl₂]have similar crystal structures,two ligands of L¹ or L² coordinated to the Cd1 atom in cis,and the central Cd1???atom has a distorted octahedral geometry?CdCl₂N₄?.The complexes of[CdL'₂?NO₃?₂]and[CdL₂³?NO₃?₂]have similar crystal structures,two ligands of L' or L³ coordinated to the Cd1 atom in cis,and the central Cd1???atom has a distorted octahedral geometry?CdN₄O₂?.3.The TGA,UV and fluorescence spectra of[Cd₂L₂??-SCN?₄]_n?[Cd₂L₂??-Cl?₄]_n?[Cd₂L'₂??-Cl?₂Cl₂?H₂O?₂]?[CdL?₂?NO₃?₂]?[CdL₂¹Cl₂]?[CdL₂²Cl₂]and[CdL₂³?NO₃?₂]were determined.All the complexes and ligands have fluorescent properties.In the fluorescence spectra of[Cd₂L₂(?-SCN₄)]_n?[Cd₂L₂??-Cl?₄]_n and[CdL?₂?NO₃?₂],blue shifts are observed compared with the ligands.