Simultaneous binding of boron and ammonium cation by a pseudocryptand: synthesis, X-ray analysis and solution studies by NMR spectroscopy

Abstract

Treatment of the macrocyclic compound 1 bearing two catecholate moieties with equimolar amounts of B(OH)3 and aqueous NH3 in a H2O–EtOH mixture gave exclusively the ammonium inclusion complex 2 which was then studied both in solution and in the solid state; the selectivity sequence NH4+ > Na+ > Cs+ in CD3OD solution was obtained and the ammonium ion complex 2 was found to be more stable than the ([222], NH4+) complex by at least 3 orders of magnitude.