Effect of the size of discrete anions on the nuclearity of a complex cation

Abstract

Reactions of 2,3-diphenylquinoxaline (L) with AgClO₄·xH₂O, AgCF₃SO₃, AgBF₄, AgCF₃CO₂ and AgNO₃ in equimolar proportions at room temperature yield, respectively, AgL·ClO₄·2CH₃OH (1), AgL₂·CF₃SO₃ (2), AgL·BF₄·H₂O·½C₂H₅OH (3), AgL₂·CF₃CO₂ (4) and Ag·½L·NO₃ (5). From X-ray crystallography, complexes 1, 3 and 5 are found to be 1-D hybrid polymers while 2 and 4 are mononuclear. In these five structures, only the nitrate anion is found to be coordinating; other anions are more or less non-coordinating. For the non-coordinating anions, it is concluded that small anions lead to a polymeric cationic complex and larger ones exert a non-proliferating effect in the countercation. In 1 and 3 the polymerization in the complex cation is brought about by bidentate L. But in 5, the anion also becomes a part of the polymeric assembly. The nature of the solvent seems to have little effect on these general observations.