Syntheses, Crystal Structures And Characterization Of The Complexes Of 2?substituted?5?pyridyl?1,3,4?thiadiazole

1,3,4-Thiadiazoles are important heterocyclic compounds widely used in the fields of pesticides,medicines and chemical materials.In order to study the 1,3,4-thiadiazole transition metal complexes,we synthesized six novel 2-substituted-5-pyridyl-1,3,4-thiadiazole compounds,and the crystal structures and properties of the complexes were investigated.The works in this paper are as follows.1.Six 2-substituted-5-pyridyl-1,3,4-thiadiazole compounds were synthesized.The ultraviolet and fluorescence spectra of the 2-methyl-5-（2-pyridyl）-1,3,4-thiadiazole（L）and2-（p-methylphenyl）-5-（2-pyridyl）-1,3,4-thiadiazole（L’）were determined,and the fluorescence emission wavelength of λ_max are 415 nm and 390 nm,respectively.2.Seven metal complexes are prepared from 2-methyl-5-（2-pyridyl）-1,3,4-thiadiazole（L）and 2-（p-methylphenyl）-5-（2-pyridyl）-1,3,4-thiadiazole（L’）,and their crystal structures were determined.The complex of[CuL₂Cl₂]·2H₂O is a monomeric metal complex,and the central copper（Ⅱ）atom has a distorted octahedral geometry（CdN₄Cl₂）.The complexes of[CdL₂（NO₃）₂]and[CdL’₂（NO₃）₂]·1.5H₂O have similar structures.The central cadmium（Ⅱ）atoms have distorted octahedral geometries（CdN₄O₂）,and the two ligands are in cis.The complexes of[Ag₂（μ-L）₂（NO₃）₂]and[Ag₂（μ-L’）₂（NO₃）₂]are double-bridged dinuclear silver（（40））complexes bridged by two ligands.The central atoms of Ag1 and Ag2 have similar distorted tetrahedral geometries with AgN₃O.The complex of[Cd₂L₂（μ-Cl）₄]_n is a double-bridged cadmium（Ⅱ）polymeric complex bridged by two chloride ions,and the central cadmium（Ⅱ）atoms have distorted octahedral geometries with CdCl₄N₂.The complex of[Cd₂L₂（μ-SCN）₄]_n is a double-bridged cadmium（Ⅱ）polymeric complex bridged by two thiocyanate ions,and the central cadmium（Ⅱ）atoms have distorted octahedral geometries with CdN₄S₂.3.The TGA,UV and fluorescence spectra of[CuL₂Cl₂]·2H₂O,[CdL₂（NO₃）₂],[Ag₂（μ-L）₂（NO₃）₂],[Cd₂L₂（m-Cl）₄]_n,[Cd₂L₂（μ-SCN）₄]_n,[CdL’₂（NO₃）₂]·1.5H₂O and[Ag₂（μ-L’）₂（NO₃）₂]were measured.In the fluorescence spectra of[CuL₂Cl₂]·2H₂O,[Ag₂（μ-L）₂（NO₃）₂],[Cd₂L₂（μ-Cl）₄]_n,[Cd₂L₂（μ-SCN）₄]_n and[CdL₂（NO₃）₂],the fluorescence intensity is weaker than that of the ligand L,and blue shifts are observed.