Abstract
An N donor tetradentate manganese complex, [MnII(bispicen)Cl2] (A) [bispicen = N,N′-bis(2-pyridylmethyl)-1,2-ethanediamine)] catalyses the oxidative cleavage of 4-tert-butylcatechol (1) in the presence of O2. The oxygenated products were isolated by t.l.c. and column chromatography and characterised by 1H-, 13C-n.m.r., DEPT, i.r. and u.v.–vis. spectroscopy. The oxygenated products as well as other spectral evidence suggest that the oxygenation occurs via a 4-tert-butylsemiquinone bound complex, [MnII(bispicen)(4-sq)]+ (4-sq = 4-tert-butylsemiquinone). 1H-n.m.r. spectroscopy suggests that the oxygenation follows multiple pathways. Isolation of the products suggests that the oxygenations proceed in an extradiol fashion and a probable mechanism is suggested. Some intradiol cleaved products have also been detected. E.s.r. spectroscopy suggests that manganese(II) is ultimately converted into the manganese(IV) species.
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