Catalytic oxidations using cobalt(II) complexes - Advances in Catalytic Activation of Dioxygen by Metal Complexes - page 300

oxidation of sulfide, but oxidation is incomplete and not enhanced by
irradiation with visible light.
Zinc phthalocyanine complexes show good catalytic activity only upon
simultaneous irradiation with visible light 132 . Interaction between dioxygen
and the long-lived triplet state of these complexes produces reactive singlet
dioxygen, which also interacts with compounds containing sulfur in various
oxidation states.
Immobilized cobalt(II) and zinc(II)phthalocyanine anchored on silica or
intercalated in the galleries and cavities of layered double hydroxides
(hydrotalcite) and NaX zeolite catalyze or photocatalyze the oxidation of 2-
mercaptoethanol and sodium thiosulfate 133 . The activity of the immobilized
catalysts for oxidation and photooxidation is lower than that of the
complexes in homogeneous phase. This is due to the hindered diffusion of
dioxygen and sulfur-containing compounds to the active catalyst sites.
The six-coordinate low-spin cobalt(III) complexes
and (pc = phthalocyaninate, py = pyridine,
dce = 1,2-dichloroethane and thf = tetrahydrofuran) oxidize terminal olefins
to the corresponding methyl ketones 134 .
Dioxygen activation and oxygen-atom transfer reactions are possible in
terms of the redox couple 135 .
Particulate and solubilized cobalt(II) phthalocyanines (PCs) exhibit cata-
lytic activity in the oxidative decomposition of erythrosine with hydrogen
peroxide 136 .