Uptake of oxygen by ammoniacal cobalt(II) solutions

Dioxygen affinities and catalytic oxidation activities of cobalt complexes with Schiff bases containing crown ether

“…4 indicate that within the measured temperature range the maximum dioxygen uptake and oxygenation constants of cobalt complexes will decrease with rising temperature, but dioxygen uptake of cobalt complexes will accelerate with increasing temperature; this result is in agreement with the literature [23][24][25].…”

A Structurally Characterised Pair of Dicobalt(III) Peroxo/Superoxo Complexes withC2-Symmetrical Tetrapodal Pentadentate Amine Ligands, and Some Reactivity en route

“…Simplicio and Wilkins showed that oxygen uptake by ammoniacal cobalt(II) solutions is due mainly to the reaction of the pentakis(ammine) aqua complex [Co(NH 3 ) 5 [27,28] While such species do add oxygen when the nitrogen donor atoms are incorporated into chelate ligands, oxygenation is clearly enhanced as a consequence of an increasing number of ammine or amino groups coordinated to cobalt. [11] A variety of chelating pentaamines, including an early example of a tetrapodal pentadentate ligand, [29,30] have been investigated in this context, and a number of µperoxo complexes thus obtained have been structurally characterised.…”

“…With a view to studying the effect of an external reducing agent on the generation of the peroxo complex 8 from Na 3 [Co(CO 3 ) 3 ]⋅3H 2 O and 1⋅4HBr⋅MeOH in air, we reacted two equivalents each of the cobaltate and the pentaamine ligand in the presence of one equivalent of sodium dithionite in water, which contained an excess of NaHCO 3 (Na 2 S 2 O 4 has been used to decompose Co II ϪO 2 adducts, but the product(s) deriving from the dithionite ion have never been identified [27] ). The only isolated products of this reaction were a finely divided black solid (which tested positive for S 2Ϫ and is presumably Co 2 S 3 ) and an orangebrown microcrystalline precipitate identified as the S-sulfito complex [(1)CoSO 3 ]Br (13) by elemental and X-ray structural analysis (yield accounts for 39% of the pentaamine ligand 1).…”

Novel homogeneous catalyst system for the oxidation of concentrated ammonium sulfite

“…A brown binuclear complex, with bridging dioxygen, is formed; decrease of the oxygen pressure or increase of the ammonia concentration deoxygenates the complex [12,13]:…”