Oxygen chemisorption by γ-Al2O3 phthalocyaninato cobalt(II) : Influence of the surface species γ-Al 2O3 on O2- fixation

The degree of hydration of the γ-Al2O3 surface governs (a) the type of interaction between phthalocyaninato cobalt(II), [Co(pc)], and γ-Al2O3; (b) the activation of [Co(pc)] towards O2 reduction; (c) the fixation of O2- to Al3+ centres. Thermal, spectroscopic and spectromagnetic analyses show that: (a) the complex [Co(pc)] interacts with the support, as expected for a basic molecule fixed to an acidic surface; (b) O 2 is reduced by the cobalt complex; (c) the initial stage of interaction between γ-Al2O3[Co(pc)] and O 2 is formation of the adduct [Co(pc)]O2 on the γ-Al2O3 surface, followed by O2- fixation on the Al3+ centres. Competition exists between [Co(pc)] and Al3+ as for O2- coordination.