Dioxygen affinities and catalytic oxidation performance of cobalt(II) hydroxamates with benzo-15-crown-5 pendants

The oxygenation constants (KO2)(KO2) of cobalt(II) hydroxamates (CoL21–CoL23) with benzo-15-crown-5 (B15C5) pendants were measured over the range of −5 to +20 °C, and the values of thermodynamic parameters (ΔH0 and ΔS0) were calculated based on these (KO2)(KO2) values. Meanwhile, these crowned complexes were employed to the oxidation for p-xylene to p-toluic acid with air at 110Δ under normal atmospheric pressure. The effects of B15C5 pendant and the length of chain bonded to B15C5 in these complexes on the O2-binding capabilities and oxidation for p  -xylene were investigated with the comparison of crown-free analogues CoL24.