Silver coordination and hydrogen bonds: A study of competing forces

A series of six bipyridyl ligands, amino-methylpyridine ureas, and oxalamid es have been synthesized and complexes with silver salts have been prepared . The 3-pyridyl ligands form silver complexes with a 2:1 ligand to metal ra tio: Ag(3u)(2)BF4, Ag(3o)(2)BF4, and Ag(3o)(2)NO3. In these three complexes the ligands form hydrogen-bonded one-dimensional or-networks in accordance with an anticipated design. Each silver cation is four coordinate, bringin g four of the ex-networks together to form a channeled solid. The anions, N O3- or BF4-, occupy the channels. The 4-pyridyl and 2-pyridyl ligands form silver complexes with a 1:1 ligand-to-metal ratio. The silver cations of th e 3-pyridyl ligand complexes, Ag(4u)NO3. H2O and Ag(4o)NO3, have linear two coordination geometries. The 2-pyridyl urea complex, Ag(2u)BF4, features a three-coordinate silver cation with the third bond coming from the oxygen atom of a neighboring urea functionality. This results in a unique ladder s tructure. The 2-pyridyl oxalamide structure, Ag(2u)BF4, has two-coordinate silver cations and is helical, with a hydrogen bond between neighboring oxa lamide functionalities. (C) 1999 Elsevier Science Ltd.