Abstract
Reaction of Cu(BF4)(2) center dot 6H(2)O with the N3O2 donor ligand H2L (where H2L = N-benzyl- N', N ''-di-tert-butyl-disalicyl- triaminocyclohexane) results in the formation of a novel (CuL)-L-II complex, 1. X-Ray crystallography of 1 shows the Cu-II centre coordinated by two phenolate oxygens and two imine nitrogens in a distorted square plane with an elongated bond to the amine nitrogen (2.512 angstrom) in the axial position. EPR spectroscopy of 1 gives g values of g(1) = 2.277, g(2) = 2.100, g(3) = 2.025, and A(1) = 15.6 mT which are consistent with the distorted square pyramidal coordination environment determined from the X-ray structure. UV/visible and electrochemical analysis of 1 shows that it undergoes two reversible processes assigned to the successive oxidation of the phenolate oxygens to phenoxyl radicals, the first at E-1/2 = 0.89 V (Delta E = 81 mV, vs. Ag/AgCl) and the second at E-1/2 = 1.13 V (Delta E = 84 mV, vs. Ag/AgCl). Chemical oxidation of 1 results in the formation of a species, assigned as [1](+center dot) which is EPR silent due to antiferromagnetic coupling between the Cu-II centre and the bound phenoxyl radical. The oxidised species catalyses the oxidation of benzyl alcohol to benzaldehyde.
Original language | English |
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Pages (from-to) | 172-176 |
Number of pages | 5 |
Journal | Dalton Transactions |
Volume | 1 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2006 |
Keywords
- PHENOXYL RADICAL COMPLEXES
- GALACTOSE-OXIDASE MODELS
- N-PYRIDYL DERIVATIVES
- OXIDIZED ACTIVE FORM
- STRUCTURAL MODELS
- ONE-ELECTRON
- SITE MODELS
- CHEMISTRY
- MONONUCLEAR
- REACTIVITY