Synthesis and Characterization of New Coordination Polymers Generated from Oxadiazole-Containing Organic Ligands and Inorganic Silver(I) Salts

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole
(L2) and 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (L3) with inorganic Ag(I) salts has been investigated. Four new
coordination polymers were prepared by solution reactions and fully characterized by infrared spectroscopy, elemental
analysis, and single-crystal X-ray diffraction. {[Ag(L2)]SO3CF3}n (1) (triclinic, P1̄; a = 10.1231(7) Å, b = 13.9340(10) Å, c = 13.9284(10) Å, α = 116.7300(10)°, β = 94.6890(10)°, γ = 108.7540(10)°, Z = 4) was obtained by
the combination of L2 with AgOTf in a CH2Cl2/CH3OH mixed-solvent system and features a unique one-dimensional
elliptical macrocycle-containing chain motif. The approximate dimensions of the rings are ca. 22 × 11 Å. {[Ag(L2)](ClO4)(CH3OH)0.5(H2O)0.5}n (2) (triclinic, P1̄; a = 8.4894(5) Å, b = 13.9092(8) Å, c = 14.1596(8) Å, α =
71.1410(10)°, β = 77.3350(10)°, γ = 81.5370(10)°, Z = 4) was generated from the reaction of L2 with AgClO4
in a H2O/CH3OH mixed-solvent system and consists of one-dimensional chains that are linked to each other by
weak noncovalent π-π interactions into two-dimensional sheets. Uncoordinated ClO4- counterions and guest solvent
molecules are located between the layers. {[Ag(L2)]NO3}n (3) was obtained by the combination of L2 with Ag(NO3)2 in a MeOH/H2O mixed-solvent system (triclinic, P1̄; a = 8.3155(6) Å, b = 8.8521(6) Å, c = 9.8070(7) Å,
α = 74.8420(10)°, β = 77.2800(10)°, γ = 68.6760(10)°, Z = 2). In the solid state, it exhibits an interesting pair
of chains associated with C−H···O hydrogen bonds. {[Ag(L3)]SO3CF3}n (4) is generated from L3 and AgSO3CF3
in a CH2Cl2/MeOH mixed-solvent system and crystallizes in the unusual space group Pnnm, with a = 7.9341(4)
Å, b = 11.5500(5) Å, c = 18.1157(8) Å, and Z = 4. It adopts a novel three-dimensional structural motif in the solid
state with big rhombic channels (ca. 15 × 10 Å).