Investigation of Exogenous Substrate Reactivity

with a [Cu(III)2O2]2+ Core.

    

                      SvitlanaV. Pavlova, Chiu-Fou Tseng, and Sunney I. Chan

 

                      Institute of Chemistry, Academia Sinica, Taipei 115, Taiwan.  

 

    The bis-μ-oxodicopper  [Cu(III)2O2]2+ core has been proposed as an reactive intermediate involved in oxidation  chemistry mediated  by copper-containing enzymes and  other  catalysts.  Complexes with μ-η2:η2- peroxodicopper(II) and bis-μ-oxodicopper(III) core are now well characterized.  It has been shown  that with bidentate amine or mixed  pyridyl/amine donor ligands, these complexes are capable of ligand hydroxylation of aromatic and aliphatic group, but  they are relatively inert towards hydrocarbon hydroxylation. Studies of alkene oxidation are limited to a few cases.

    In the order to investigate the ability of dicopper complexes with [Cu(III)2O2]2+ core towards oxidation/epoxidation of  alkene, a series of  known complexes  [L(1-3)Cu(III)2O2]2+  (where L1-N,N,N’,N’-tetramethyl-(1,3)-propanediamine,  L2 - N,N,N’N’-tetramethyl-(1R,2R)-cyclohexanediamine,

L3-N,N,N’N’-tetraethylethylenediamine) were synthesized and their reactions with alkenes (propene,butene,stilbene) have been studied. The oxidation of alkenes was examined   at –400, - 800 in anaerobic condition. EPR and optical spectroscopy  have been used for structural characterization of the complexes obtained. The products of the  reaction were examined by GC, GC/MS analysis. Towards  testing a hypothesis that the  chemistry of [Cu(III)2O2]2+  may become extremely facile when one of the Cu(III)’ in the cluster becomes reduced, the reactivity of fully oxidized bis-μ-oxodicopper(III)complex have also been compared with  the reactivity  of a mixture(50-50) of bis-μ-oxodicopper(III)complex with suitable reductant( Cu(I) precursor).  These  experimental results will be discussed.

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