Synthesis and characterization of new coordination polymers generated from oxadiazole-containing organic ligands and inorganic silver(I) salts.

Abstract

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, P1; a = 10.1231(7) A, b = 13.9340-(10) A, c = 13.9284(10) A, alpha = 116.7300(10) degrees, beta = 94.6890(10) degrees, gamma = 108.7540(10) degrees, 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 x 11 A. [[Ag-(L2)](ClO4)(CH3OH)0.5(H2O)0.5]n (2) (triclinic, P1; a = 8.4894(5) A, b = 13.9092(8) A, c = 14.1596(8) A, alpha = 71.1410(10) degrees, beta = 77.3350(10) degrees, gamma = 81.5370(10) degrees, 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 pi-pi 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, P1; a = 8.3155(6) A, b = 8.8521(6) A, c = 9.8070(7) A, alpha = 74.8420(10) degrees, beta = 77.2800(10) degrees, gamma = 68.6760(10) degrees, 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) A, b = 11.5500(5) A, c = 18.1157(8) A, and Z = 4. It adopts a novel three-dimensional structural motif in the solid state with big rhombic channels (ca. 15 x 10 A).