Branched non-covalent complexes between carboxylic acids and two tris(amidines)

Abstract

Carboxylic acids and two tris(amidine) bases formed branched 3∶1 complexes with high solubility in chlorinated and aromatic solvents, particularly when aromatic carboxylic acids with suitable solubilising substituents were used. Whereas N,N′-diethylamidine complexes 10 proved to be difficult to isolate, the respective imidazoline complexes 14 were easily purified by crystallisation. Association constants were determined for model bis(imidazoline) complexes to be about 10³ dm³ mol^–1 in the competitive solvent mixture CDCl₃–CD₃OD (97∶3).