Assembly via H-bonds and Ag-Ag attractions of one-dimensional silver(I) complexes of nicotinamide and nicotinic acid with sulfonate counter-anions

Three silver(I) complexes containing pyridine derivatives have been synthesized and structurally characterized by X-ray single crystal diffraction, in order to evaluate the effect of counter anions upon the assembly process of complex cations via intermolecular hydrogen bonds. [Ag(nia)(2)](2)(bpds).2H(2)O (1) and [Ag(nia)(2)](asa) (2) (nia=nicotinamide, bpds=4,4'-biphenyldisulfonate, asa=aminosulfonate) contain cationic complexes comprised of two nicotinamide ligands coordinated with the pyridine nitrogen atoms to a silver(I) ion in a linear fashion. The linear unit is connected to another one by a weak Ag-Ag interaction leading to an H-shaped dimeric unit. The dimeric units are linked through hydrogen bonds formed between amide groups in a head-to-head mode, creating one-dimensional cationic ribbons. In 1, the ribbons are extended into two-dimensional network via hydrogen bonds formed by the amide groups. The cationic complex cations in [Ag(niac)(2)](2)(1,5nds).2H(2)O (3) (niac=nicotinic acid, 1,5nds=1,5-disulfonate) are also connected to each other through Ag-Ag interactions, leading to H-shaped dimeric units. The dimeric units are propagated via C-H...O hydrogen bonds between the aromatic hydrogen atom and the carbonyl oxygen. A database search shows that the unique Ag-Ag interaction between the discrete silver(I) coordinated linearly just by two pyridine nitrogen atoms is only observed in salts containing sulfonate or sulfate as counter anions. (C) 2002 Published by Elsevier Science Ltd.