New polymeric networks from the self-assembly of silver(I) salts and the flexible ligand 1,3-bis(4-pyridyl)propane (bpp) : a systematic investigation of the effects of the counterions and a survey of the coordination polymers base on bpp

The self-assembly of polymeric networks from different Ag(I) salts and the flexible ligand 1.3-bis(4- pyridyl)propane (bpp) has been systematically investigated in order to obtain some basic information useful for the crystal engineering of coordination frames upon variation of the counterions. The salts AgNO3, AgBF4, AgClO4, AgPF6, AgAsF6 and AgSbF6 have been reacted in the molar ratio Ag: bpp of 1 : 2. Though in some cases wee have observed the formation of mixtures, containing also minor amounts of the 1 : 1 adducts [Ag(bpp)]X, the [Ag(bpp)(2)]X. derivatives have been obtained for all the salts, and all of the isolated crystalline products have been characterized by single-crystal X-ray analysis. Polymeric 2D and 3D networks have been observed, exhibiting fear different structural motifs: [Ag(bpp)(2)](NO3) (1) contains 2D layers of square meshes that show 2-fold parallel interpenetration; compounds [Ag(bpp)(2)](BF4) (2) and [Ag(bpp)(2)](ClO4) (3) are isomorphous and contain 2-fold interpenetrated diamondoid networks: more surprisingly, compounds [Ag(bpp)(2)](PF6) (4) and [Ag(bpp)(2)](PF6) (5) show a wafer-like structure containing, for the first tune, 2-fold entangled (4,4) layers alternated to simple (4.4) layers; and finally, [Ag (bpp)(2)](SbF6) (6) contains single 2D layers of tessellated 4-membered rings. A brief analysis of the known coordination polymers based on the bpp ligand is also reported, including the structure of the novel species [Cu(NO3)(2)(bpp)](2).2CH(2)Cl(2), a molecular ring that represents the unique example showing the GG conformation for the bpp ligands.