DIOXYGEN ADDUCTS OF COBALT(II) COMPLEXES OF 6,6'-BIS(P-SUBSTITUTED BENZOYLAMINO)-2,2'-BIPYRIDINES AND THEIR CATALYTIC ACTIVITIES IN OXYGENATION OF 2,6-DI-TERT-BUTYLPHENOL
K. Araki et al., DIOXYGEN ADDUCTS OF COBALT(II) COMPLEXES OF 6,6'-BIS(P-SUBSTITUTED BENZOYLAMINO)-2,2'-BIPYRIDINES AND THEIR CATALYTIC ACTIVITIES IN OXYGENATION OF 2,6-DI-TERT-BUTYLPHENOL, Journal of the Chemical Society. Dalton transactions, (24), 1993, pp. 3647-3651
The oxygen affinities and properties of oxygen adducts of complexes [C
oL] [H-2L = 6,6'-bis(benzoyl-amino)-2,2'-bipyridine and its 4-methyl-,
-tert-butyl or -chloro-benzoylamino analogues] has been studied by cy
clic voltammetry and IR, electronic and ESR spectroscopy. The complexe
s exhibited oxygen-binding ability in the presence of an appropriate a
xial base ligand (B), and the oxygen adducts were of the end-on bonded
Co(III) (O2) type [CoL(B)(O2)]. More complete electron transfer from
the metal centre to the oxygen was indicated compared to that with [Co
(salen)] [H-2salen = N,N'-ethylenebis(salicylideneimine)]. Electron-do
nating substituents gave higher concentrations of the oxygen adducts.
The superior catalytic activity of these complexes, especially the Me-
and Bu(t)-substituted derivatives, in the oxygenation of 2,6-di-tert-
butylphenol to the corresponding quinone is interpreted in terms of th
e reactivity of the co-ordinated oxygen and the oxygen affinity of the
complexes.