Acid-catalysed hydrolysis of some trans-dinitrocobalt(III) complexes of cyclic quadridentate ligands

Abstract

The replacement of nitro-group from the complexes trans-[Co(A₄)(NO₂)₂]ClO₄[where A₄= 1,4,8,11-tetraazacyclotetradecane(cyclam) or its 5,7,7,12,14,14-hexamethylated analogue (teta)] in aqueous solutions of strong acids at low temperatures has been studied. In these systems maximum rates corresponding to complete protonation were observed. However, as the acid concentration increases still further the rate of hydrolysis decreases; this is in marked contrast to the behaviour of the azido-systems studied earlier. The possible reasons for these observations are discussed in terms of the species present in the solutions.