Pitfalls in the supramolecular assembly of silver(I) coordination compounds

The syntheses and crystal structures of (6-methylnicotinic acid) (6- methylnicotinato)silver(I), di (6-methylnicotinic acid) silver(I) nitrate, (2-chloro-6-methylnicotinato) silver(I), di (2-chloro-6-methylnicotinic acid) silver(I) nitrate, and (2-methylnicotinic acid) (2-methylnicotinato) silver(I) are described. These coordination complexes were synthesized under the same conditions and with very similar ligands but their resulting structures are quite different, in part due to the degree of protonation of the nicotinic acid ligand(s). The structures vary from coordination polymers to hydrogen-bonded coordination dimers, to linear structures linked by anion-carboxylic acid hydrogen bonds. This study illustrates some of the difficulties involved in predicting hydrogen-bonded networks in transition-metal systems which contain carboxylic acid moieties and coordinatively unsaturated metal ions. (C) 1998 Elsevier Science B.V. All rights reserved.