Effects of electron-deficient beta-diketiminate and formazan supporting ligands on copper(I)-mediated dioxygen activation.
Copper(I) complexes of a diketiminate featuring CF(3) groups on the backbone and dimethylphenyl substituents (4) and a nitroformazan (5) were synthesized and shown by spectroscopy, X-ray crystallography, cyclic voltammetry, and theory to contain copper(I) sites electron-deficient relative to those supported by previously studied diketiminate complexes comprising alkyl or aryl backbone substituents. Despite their electron-poor nature, oxygenation of LCu(CH(3)CN) (L = 4 or 5) at room temperature yielded bis(hydroxo)dicopper(II) compounds and at -80 degrees C yielded bis(mu-oxo)dicopper complexes that were identified on the basis of UV-vis and resonance Raman spectroscopy, spectrophotometric titration results (2:1 Cu/O(2) ratio), electron paramagnetic resonance spectroscopy (silent), and density functional theory calculations. The bis(mu-oxo)dicopper complex supported by 5 exhibited unusual spectroscopic properties and decayed via a novel intermediate proposed to be a metallaverdazyl radical complex, findings that highlight the potential for the formazan ligand to exhibit "noninnocent" behavior.
Hong
Sungjun
S
Department of Chemistry, Center for Metals in Biocatalysis, and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, USA.
Hill
Lyndal M R
LM
Gupta
Aalo K
AK
Naab
Benjamin D
BD
Gilroy
Joe B
JB
Hicks
Robin G
RG
Cramer
Christopher J
CJ
Tolman
William B
WB
D003300:Copper / Q000737:chemistry*; D004583:Electrons; D005562:Formazans / Q000737:chemistry*; D005609:Free Radicals; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013057:Spectrum Analysis
D005562:Formazans; D005609:Free Radicals; D007097:Imines; D008024:Ligands; D009942:Organometallic Compounds; D003300:Copper; D010100:Oxygen