53539-63-2Relevant articles and documents
Regioselective Formation of Peroxyquinolatocobalt(III) Complexes in the Oxygenation of 2,6-DI-t-butylphenols Schiff-base Complexes
Nishinaga, Akira,Tomita, Haruo,Nishizawa, Kanji,Matsuura, Teruo,Ooi, Shunichiro,Hirotsu, Ken
, p. 1504 - 1514 (2007/10/02)
The oxygenation of 2,6-di-t-butylphenols with five-co-ordinated cobalt(II) Schiff-base complexes in aprotic solvents, such as CH2Cl2, thf, and dmf (thf = tetrahydrofuran, dmf = dimethylformamide), has been found to result in regioselective formation of peroxyquinolatocobalt(III) complexes.The regioselectivity depends on the nature of the substituent at the 4-position of the phenol used: 4-alkyl-2,6-di-t-butylphenols(1) afford peroxy-p-quinolatocobalt(III) complexes, whereas peroxy-o-quinolato-complexes are formed from 4-aryl-2,6-di-t-butyl-phenols (4).The initiation of the oxygenation is hydrogen abstraction by superoxocobalt(III) species from the phenols to give the corresponding phenoxy-radicals (10).Rapid reduction of (10) with cobalt(II) species follows giving rise to a phenolatocobalt(III) complex intermediate, within which dioxygen is incorporated.The regioselectivity of the oxygenation is attributable to the formation of the phenolatocobalt(III) complex intermediate.Crystals of the peroxy-p-quinolatocobalt(III) complex (2a) are orthorombic, space group P212121, with a = 33.749(11), b = 11.844(5), c = 9.329(4) Angstroem, and Z = 4.The crystal structure has been refined from 3 018 diffractometer data to R = 0.067.
