Abstract: In this article the equilibrium constant and enthalpy for formation of the dioxygen adduct of the bis (sa1icyliden-iminato-3-propyl) methylaminocobalt (II) complex (CoSMDPT) are reported in methylene chloride solution (-9.8 kcal mol-'). When small amounts of 2, 2, 2- trifluoroethanoI (TFE) are added, extra stabilization of the dioxygen adduct is found. The measured enthalpy for adduct formation increases to-1 1.8 kcal mol-'. Infrared frequency ...