Silver coordination and hydrogen bonds: a study of competing forces

Abstract

A series of six bipyridyl ligands, amino-methylpyridine ureas, and oxalamides 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 ratio: Ag( 3u) 2BF 4, Ag( 3o) 2BF 4, and Ag( 3o) 2NO 3. In these three complexes the ligands form hydrogen-bonded one-dimensional α-networks in accordance with an anticipated design. Each silver cation is four coordinate, bringing four of the α-networks together to form a channeled solid. The anions, NO 3 − or BF 4 −, 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 the 4-pyridyl ligand complexes, Ag( 4u)NO 3·H 2O and Ag( 4o)NO 3, have linear two coordination geometries. The 2-pyridyl urea complex, Ag( 2u)BF 4, 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 structure. The 2-pyridyl oxalamide structure, Ag( 2u)BF 4, has two-coordinate silver cations and is helical, with a hydrogen bond between neighboring oxalamide functionalities.