Synthesis, characterization and acid hydrolysis of [N,N-bis(2-aminoethyl)-1,2-ethanediamine]bis(solvent)cobalt(III) complexes

Abstract

Synthesis of the precursor [N,N-bis(2-aminoethyl)-1,2-ethanediamine]bis(trifluoromethanesulphonato-O)cobalt(III) trifluoromethanesulphonate allowed facile synthesis of the bis(dimethyl sulphoxide), bis(dimethylformamide), bis(trimethyl phosphate), and bis(acetonitrile) complexes by solvolysis of the trifluoromethanesulphonato-complex in dry solvents. The new bis(solvent) complexes were characterized by spectroscopic methods and by microanalysis. In aqueous acid, they hydrolyse in two consecutive steps which differ in rate by a factor of less than ten. While the complexes are stereochemically rigid as a consequence of co-ordination of the N,N-bis(2-aminoethyl)-1,2-ethanediamine tripodal ligand, the observed rate constants are composite terms since the two solvent ligands are in non-equivalent sites, and initial ligand loss from both sites occurs. N.m.r. experiments reveal that this loss proceeds at similar rates for each site.