Characterization of a 1:1 Cu-O2 adduct supported by an anilido imine ligand.
Copper(I) complexes of sterically hindered anilido imine ligands o-C6H4{N(C6H3(i)Pr2)}{C(R)=NC6H3(i)Pr2}- (L(1), R = H; L(2), R = CH3) have been prepared and characterized by spectroscopic and X-ray crystallographic methods. These complexes are highly reactive with O2, and in the case of L2 the product of low-temperature oxygenation was fully characterized by spectroscopic, X-ray crystallographic, and computational methods. The resonance Raman spectrum features an isotope-sensitive vibration at 974 cm(-1) (Delta(18O) = 66 cm(-1)), consistent with assignment as an O-O stretch. Despite the asymmetric coordination environment provided by the supporting anilido imine ligand, the X-ray crystal structure confirms rather symmetric side-on binding of the O2 moiety to the copper center, and the O-O bond length of 1.392(2) Angstroms indicates that this intermediate has significant Cu(III)-peroxo character. Theoretical calculations support this interpretation and predict that while a fully optimized end-on singlet geometry can be obtained, it is higher in energy than the side-on isomer by 3.5 kcal mol(-1) at the CASPT2/TZP level.
Reynolds
Anne M
AM
Department of Chemistry, University of Minnesota, Minneapolis, 55455, USA.
Gherman
Benjamin F
BF
Cramer
Christopher J
CJ
Tolman
William B
WB
D000813:Anilides / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D013053:Spectrophotometry
D000813:Anilides; D007097:Imines; D008024:Ligands; D003300:Copper; C030973:cupric oxide