Aerial oxidation of primary alcohols and amines catalyzed by Cu(II) complexes of 2,2'-selenobis(4,6-di-tert-butylphenol) providing [O,Se,O]-donor atoms.
Seven copper(II)-complexes 1-7 with the ligand 2,2'-selenobis(4,6-di-tert-butylphenol) providing [O,Se,O]-donor atoms have been isolated and characterized. Three of them 1, 2 and 3 are mononuclear, two 4 and 7 dinuclear and 5, 6 are trinuclear. The crystal structures of the complexes were determined by X-ray diffraction and the electronic structures were established by various physical methods including EPR and variable temperature (2-290 K) susceptibility measurements. The magnetic behaviour of the compounds 4-6 exhibits antiferromagnetic exchange coupling resulting in well-isolated S(t)= 1/2 ground state for 5 and 6 and a diamagnetic spin state for 4. Complexes 5 and 6 belong to the class of asymmetric trinuclear copper(II) complexes modelling the trinuclear copper site in multicopper oxidases. Complex 1 is a catalyst in the presence of a strong base for the aerial oxidation of primary alcohols to the corresponding aldehydes. A dinuclear complex, seemed to be 4, prepared in situ has been found to be a catalyst for the aerial oxidation of primary amines containing alpha-C-H atoms. Primary kinetic isotope effects show that H-abstraction from the alpha-carbon atom of a coordinated substrate (alcoholato or amine) is the rate-determining step in both cases. Two functional models for the metalloenzymes galactose oxidase and amine oxidases are thus described.
Paine
Tapan K
TK
Max-Planck-Institut fur Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mulheim an der Ruhr, Germany.
Weyhermüller
Thomas
T
Wieghardt
Karl
K
Chaudhuri
Phalguni
P
D000438:Alcohols / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D001547:Benzaldehydes / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D008280:Magnetics; D015394:Molecular Structure; D016566:Organoselenium Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry*; D013057:Spectrum Analysis; D014961:X-Ray Diffraction
C511191:2,2'-selenobis(4,6-di-tert-butylphenol); D000438:Alcohols; D000588:Amines; D001547:Benzaldehydes; D016566:Organoselenium Compounds; D010636:Phenols; D003300:Copper; D012643:Selenium; D010100:Oxygen; C032175:benzaldehyde