| Abstract
| - A new polyimidazole tripod N,N-bis((1-methyl-4-pivalamidoimidazol-2-yl)methyl)-N‘-((1-methylimidazol-2-yl)methyl)amine (L2) has been synthesized and shown to form intramolecular hydrogen bonds with different axial ligandsbonded to Cu(II) in the solid state. The same hydrogen-bonding property of L2 appears responsible for the stabilizationof a Cu(II)−OOH species in solution. The crystal structures of L2 and three of its Cu(II) complexes are reported.The [Cu(L2)X]ClO4 complexes, 4−6 (X- = Cl-, OH-, or N3-) have distorted trigonal bipyramidal geometries in thesolid state and have been characterized further by UV−vis absorption, electron paramagnetic resonance (EPR)spectroscopy, and cyclic voltammetry. The reaction of [Cu(L2)OH](ClO4) (5) with H2O2 and tert-butyl hydroperoxidein methanol generates [Cu(L2)OOH](ClO4) (7) and [Cu(L2)OOtBu](ClO4) (8) which have been characterized bydifferent spectroscopic methods. The compound [Cu(L2)OOtBu]+ displays a band at 395 nm (ε = 950 M-1 cm-1)assigned to an alkylperoxo π*σ → Cu ligand-to-metal charge transfer (LMCT) transition, while [Cu(L2)OOH]+ displaysa peroxo π*σ → Cu charge-transfer transition at 365 nm with ε = 1300 M-1 cm-1, a mass ion at m/z 593.4, andνO-O stretch (resonance Raman) at 854 cm-1 that shifts to lower energy by 46 cm-1 upon 18O substitution.
- A new amide functionalized imidazole tripod (L2) has been synthesized and used to form several copper(II) complexes having the general formula [Cu(L2)X](ClO4), where X = Cl-, OH-, N3-, OOH-, or OOtBu-. L2 and its metal complexes have been characterized by different physical methods, which include X-ray crystallography, ESI-MS, IR, UV−vis, EPR, resonance Raman spectroscopy, and cyclic voltammetry. Spectroscopic evidence is presented in support of end-on coordination of a hydroperoxo ligand.
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