EQUILIBRIUM STUDIES OF 1,2-DIAMINOBENZENE AND 3,4-DIAMINOBENZOATE ANION WITH DINUCLEAR COBALT(II) 1,4,7,13,16,19-HEXAAZA-10,22-DIOXACYCLOTETRACOSANE

1,2-Diaminobenzene and 3,4-diaminobenzoate bridge two cobalt centers i n the cavity of the macrocycle 1,4,7,13,16,19-hexaaza-10,22-dioxacyclo tetracosane (OBISDIEN), under both anaerobic and aerobic conditions, s tabilizing the binuclear array. Under dioxygen mu-peroxo mu-hydroxo br idges are also formed at p[H] values above 6. These dinuclear complex systems were characterized by potentiometric titration and UV-Vis spec trophotometric measurements. Equilibrium constants for ail major compl exes formed are reported, and the results are presented in the form of distribution diagrams, showing the concentrations of individual speci es as a function of p[H]. Coordinate bonding modes suggested for these supramolecular complexes show the proposed oxidant (a mu-peroxo group ) and the substrate (mu-1,2-diaminobenzene or mu-3,4-diaminobenzoate) in close proximity, and thus facile oxidation of the substrates is exp ected.