Three-coordinate copper(I) amido and aminyl radical complexes.
A three-coordinate Cu-NR(2) system (R = p-tolyl) supported by the anionic bis(phosphino)borate ligand [Ph(2)B(CH(2)P(t)Bu(2))(2)](-) has been isolated and structurally characterized in both its anionic Cu(I) and neutral (formally) Cu(II) oxidation states. A large rate constant for the self-exchange electron-transfer reaction (k(S) >or= 10(7) M(-1) s(-1)) makes this system a functional model for the type-1 active sites in blue copper proteins. Multiedge X-ray absorption spectroscopy, multifrequency electron paramagnetic resonance, and density functional theory analyses collectively indicate that the oxidized form is best regarded as a Cu(I)-aminyl radical complex rather than a Cu(II)-amido species, with about 70% localization of the unpaired electron on the NR(2) unit. Hydrogen-atom transfer and C-C coupling reactions are presented as examples of chemical reactivity manifested by this unusual electronic structure.
Mankad
Neal P
NP
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Antholine
William E
WE
Szilagyi
Robert K
RK
Peters
Jonas C
JC
D000577:Amides; D000588:Amines; D003300:Copper; D004579:Electron Transport; D005609:Free Radicals; D007700:Kinetics; D008667:Metalloproteins / Q000737:chemistry*; D008954:Models, Biological; D008956:Models, Chemical; D010084:Oxidation-Reduction
D000577:Amides; D000588:Amines; D005609:Free Radicals; D008667:Metalloproteins; D003300:Copper