Well-defined bridged dicopper(III) chloride, azide and amino complexes

Abstract

The biologically relevant bis-(µ-L)-dicopper(III) core with modified bridging ligands (L = Cl, N3, NMe2) mimicking the enzyme oxidation bis-µ-oxo-copper(III) intermediates, was prepared from the heterocubane [Cu(CF3)2(OH)]4 and fully characterized, including X-ray crystallography. The electronic structure, effective oxidation state of copper, and natural charge distribution in these complexes were studied by DFT calculations. The oxidation state localized orbital (OSLO) method and XPS spectroscopy support a +3 oxidation state of copper in these complexes, albeit with a highly covalent Cu–C bonding, which is the most profound in the chlorido-complex. Potential of these complexes in synthetic chemistry was demonstrated on azidotrifluoromethylation of alkyne by the azido complex [Cu(CF3)2(N3)]2 furnishing a vinyl azide, and alcohol O-difluoromethylation by the copper chloride complex.