Dioxygen oxidation of hydrocarbons by a methane monooxygenase-like system: diiron complex-O_2-Zn/HOAc-MV^(2+)

The activation of dioxygen and incorporation into hydrocarbons have been achieved under mild conditions by a methane monooxygenase (MMO)-like system using a dinuclear iron complex [Fe2Dhist(OAc)2] BPh4 ·3H2O as the model complex, zinc powder as the electron donor, HOAc as the proton source and methylviologen as the electron transfer agent. The results show that styrene is oxygenated predominantly to styrene oxide (1 396 mol/100 mol of the Fe2 complex), benzaldehyde (16160) and acetophenone (986), and cyclohexane to cyclohexanol (9370) and cyclo-hexanone (2670). EPR studies indicate that the hypervalent ironoxo spiecs FeⅣFeⅣ=O, derived from FeⅢFeⅢ core via reduction, O2-binding and protonation, is the active intermediate which inserts the activated oxygen atom into C=C or C-H bond giving each product. The system closely resembles MMO and its close relative hemerythrin in the aspects of reaction phenomena, EPR characteristics and product distributions. The Mn2 analog cmplex、 Fe-Zn het-erodinuclear complex and mononuclear iron complex show no catalytic activity, indicating that dinuclear iron core is in-despansable to catalytic activity.

The activation of dioxygen and incorporation into hydrocarbons have been achieved under mild conditions by a methane monooxygenase （MMO）-like system using a dinuclear iron complex [Fe2Dhist（OAc）2]BPh4·3H2O as the model complex, zinc powder as the electron donor, HOAc as the proton source and methylviologen as the electron transfer agent. The results show that styrene is oxygenated predominantly to styrene oxide （1 396 mol/100 mol of the Fe2 complex）, benzaldehyde （16160） and acetophenone （986）, and cyclohexane to cyclohexanol （9370） and cyclohexanone （2670）. EPR studies indicate that the hypervalent ironoxo spiecs FeⅣFeⅣ（?）O, derived from FeⅢFeⅢ core via reduction, O2-binding and protonation, is the active intermediate which inserts the activated oxygen atom into C（?）C or C—H bond giving each product. The system closely resembles MMO and its close relative hemerythrin in the aspects of reaction phenomena, EPR characteristics and product distributions. The Mn2 analog cmplex、Fe-Zn