Dioxygen-bridged and monomeric cobalt(III) complexes with 1,3-Diamino-2-(aminomethyl) propane and ethylenediamine

Use of ethylenediamine (en) and the tripod ligand 1,3-diamino-2-(aminomethyl)propane (daap) results in cobalt(III)-pentamine complexes with obligate configuration. Optimization of the synthesis of [(en)(daap)Co] 2 O 2 4+ suggests that daap must undergo conformational change for complete coordination. Ultraviolet and visible spectra of [(en)(daap)Co] 2 O 2 4+ , [(en)(daap)Co] 2 O 2 5+ , [Co(daap)(enOH] 2+ , and Co-(daap)(en)H 2 O] 3+ are consistent with those of similar complexes. NMR spectra for [(en)(daap)Co] 2 O 2 4+ and for paramagnetic [(en)(daap)Co] 2 O 2 5+ were observed and assigned. The aqueous acidity of the cation [Co(daap)(en)H 2 O] 3+ was obtained at various ionic strengths.