Syntheses and characterization of dinuclear and tetranuclear Ag I I supramolecular complexes generated from symmetric and asymmetric molecular clips containing oxadiazole rings

摘要

A new asymmetric ligand, 5‐{3‐[5‐(4‐methylphenyl)‐1,3,4‐oxadiazol‐2‐yl]phenyl}‐2‐(pyridin‐3‐yl)‐1,3,4‐oxadiazole ( L5 ), which contains two oxadiazole rings, was synthesized and characterized. The assembly of symmetric 2,5‐bis(pyridin‐3‐yl)‐1,3,4‐oxadiazole ( L1 ) and asymmetric L5 with AgCO 2 CF 3 in solution yielded two novel Ag I complexes, namely catena ‐poly[[di‐μ‐trifluoroacetato‐disilver(I)]‐bis[μ‐2,5‐bis(pyridin‐3‐yl)‐1,3,4‐oxadiazole]], [Ag 2 (C 2 F 3 O 2 ) 2 (C 12 H 8 N 4 O) 2 ] n or [Ag 2 (μ 2 ‐O 2 CCF 3 ) 2 ( L1 ) 2 ] n ( 1 ), and bis(μ 3 ‐5‐{3‐[5‐(4‐methylphenyl)‐1,3,4‐oxadiazol‐2‐yl]phenyl}‐2‐(pyridin‐3‐yl)‐1,3,4‐oxadiazole)tetra‐μ 3 ‐trifluoroacetato‐tetrasilver(I) dichloromethane monosolvate, [Ag 4 (C 2 F 3 O 2 ) 4 (C 22 H 15 N 5 O 2 ) 2 ]·CH 2 Cl 2 or [Ag 2 (μ 3 ‐O 2 CCF 3 ) 2 ( L5 )] 2 ·CH 2 Cl 2 ( 2 ). Complex 1 displays a one‐dimensional ring–chain motif, where dinuclear Ag 2 (CF 3 CO 2 ) 2 units alternate with Ag 2 ( L1 ) 2 macrocycles. This structure is different from previously reported Ag– L1 complexes with different anions. Complex 2 features a tetranuclear supramolecular macrocycle, in which each ligand adopts a tridentate coordination mode with the oxadiazole ring next to the p ‐tolyl ring coordinated and that next to the pyridyl ring free. Two L5 ligands are bound to two Ag1 centres through two oxadiazole N and two pyridyl N atoms to form a macrocycle. The other two oxadiazole N atoms coordinate to the two Ag2 centres of the Ag 2 (O 2 CCF 3 ) 4 dimer. Each CF 3 CO 2 ? anion adopts a μ 3 ‐coordination mode, bridging the Ag1 and Ag2 centres to form a tetranuclear silver(I) complex. This study indicates that the donor ability of the bridging oxadiazole rings can be tuned by electron‐withdrawing and ‐donating substituents. The emission properties of ligands L1 and L5 and complexes 1 and 2 were also investigated in the solid state.