Self-Assembly of {Ag2N4}-Core-Containing Coordination Polymers from AgX (X = NO3-, ClO4-, and PF6-) and Oxadiazole-Bridged 4,4‘- and 3,3‘- Biphenylamine Ligands

Abstract

The coordination chemistry of the oxadiazole-bridged 4,4‘- and 3,3‘-biphenylamine ligands, namely, 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (L3) and 2,5-bis(3-aminophenyl)-1,3,4-oxadiazole (L4), with inorganic Ag(I) salts has been investigated. Four new coordination polymers (1−4) were synthesized from solution reactions of L3−L4 with corresponding inorganic Ag(I) salts, respectively. Compound [Ag4(L3)4(NO3)2](NO3)2·CH2Cl2 (1) (triclinic, P1̄, a = 7.5566(5) Å, b = 13.2903(8) Å, c = 17.7449(11) Å, α = 70.1790(10)°, β = 81.7940(10)°, γ = 83.4780(10)°, Z = 4) was obtained from L3 and AgNO3 in a CH2Cl2/CH3OH mixed solvent system. In 1, cationic [Ag4(L3)4(NO3)2]2+ units are connected to each other by a long Ag−O bond into one-dimensional chains, which are further linked together by eight N−H···O hydrogen-bonding systems into a three-dimensional H-bonded porous network with channels along the crystallographic a axis. [Ag(L3)]ClO4 (2) (monoclinic, I2/m, a = 8.035(2) Å, b = 17.395(5) Å, c = 11.531(4) Å, β = 103.807(4)°, Z = 4) was generated from L3 and AgClO4 in a MeOH/H2O mixed solvent system. It adopts a novel three-dimensional structural motif in the solid state with big rhombic channels (ca. 14 × 8 Å). [Ag(L4)](NO3)·0.5H2O (3) (orthorhombic, Ccca, a = 11.8508(6) Å, b = 15.8958(9) Å, c = 15.9963(9) Å, Z = 8) and Ag(L4)PF6 (4) (orthorhombic, Ccca, a = 13.225(2) Å, b = 15.998(3) Å, c = 16.049(3) Å, Z = 8) are isostructural and feature a novel two-dimensional zeolite-like net. All four new polymeric complexes contain the {Ag2N4} cluster moiety, and Ag···Ag separations are in the range of 3.36−3.83 Å.