In Situ Hydrolysis of a Ligand Based on a 1,3-Disubstituted Calix[4]Arene Derivative Functionalized with Salicylideneamine Fragments upon Complexation with Co(III) Cations

The reaction of a bis-chelate ligand based on a 1,3-disubstituted calix[4]arene containing salicylideneamine coordinating fragments on the lower rim of the macrocycle with a Lewis acid–Co(II) cations–under solvothermal conditions leads to the formation of a mononuclear complex with a metal–ligand stoichiometry of 1 : 2. Single crystal X-ray diffraction analysis revealed that during the coordination of the metal ion, which oxidizes to Co(III) under the synthesis conditions, hydrolysis of one of the two imine groups of the macrocyclic ligand occurs. The second salicylideneamine fragment and the amino group formed during the hydrolysis from two molecules of the macrocyclic ligand participate in binding the Co(III) ion, stabilizing its distorted octahedral N4O2 coordination sphere, in which the oxygen atoms are in a trans position.