ENHANCED STABILITY TO DECOMPOSITION OF A COBALT-DIOXYGEN ADDUCT SUPPORTED IN A COPOLYMER MATRIX

The decomposition of the Co-II complex of a macrocyclic cyclidene liga nd is reported both in solution and when bound to a copolymer support. E.s.r. studies show that the decomposition of the complex in pyridine solution, under an atmosphere of O-2, has an estimated half-life of c a. 36 h at 295 K. This suggests that decomposition of the O-2 adduct i s the second step observed in earlier electronic spectroscopic studies , and infers that the cyclidene O-2 adducts are much longer lived than originally thought. The Co-II cyclidene complex forms a coordinate bo nd to the pyridine group of n-butyl methacrylate/4-vinyl pyridine copo lymers and the resulting five-coordinate complexes undergo reversible oxygenation. The polymer-supported O-2 adducts are much more stable to decomposition than those in the solution phase and have an estimated half-life of ca. 30 days at 295 K. The enhanced stability to decomposi tion of the complexes in the polymer matrix is attributed to the low m obility of the complexes in the glassy polymer.