title: Steric Effect on the Nucleophilic Reactivity of Nickel(III) Peroxo Complexes.
abstract: A set of nickel(III) peroxo complexes bearing tetraazamacrocyclic ligands, [Ni(III)(TBDAP)(O2)](+) (TBDAP = N,N'-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane) and [Ni(III)(CHDAP)(O2)](+) (CHDAP = N,N'-dicyclohexyl-2,11-diaza[3.3](2,6)pyridinophane), were prepared by reacting [Ni(II)(TBDAP)(NO3)(H2O)](+) and [Ni(II)(CHDAP)(NO3)](+), respectively, with H2O2 in the presence of triethylamine. The mononuclear nickel(III) peroxo complexes were fully characterized by various physicochemical methods, such as UV-vis, electrospray ionization mass spectrometry, resonance Raman, electron paramagnetic resonance, and X-ray analysis. The spectroscopic and structural characterization clearly shows that the NiO2 cores are almost identical where the peroxo ligand is bound in a side-on fashion. However, the different steric properties of the supporting ligands were confirmed by X-ray crystallography, where the CHDAP ligand gives enough space around the Ni core compared to the TBDAP ligand. The nickel(III) peroxo complexes showed reactivity in the oxidation of aldehydes. In the aldehyde deformylation reaction, the nucleophilic reactivity of the nickel(III) peroxo complexes was highly dependent on the steric properties of the macrocyclic ligands, with a reactivity order of [Ni(III)(TBDAP)(O2)](+) < [Ni(III)(CHDAP)(O2)](+). This result provides fundamental insight into the mechanism of the structure (steric)-reactivity relationship of metal peroxo intermediates.
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Jalee
authors.initials: J
authors.lastname: Kim
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Bongki
authors.initials: B
authors.lastname: Shin
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Hyunjeong
authors.initials: H
authors.lastname: Kim
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Junhyung
authors.initials: J
authors.lastname: Lee
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Joongoo
authors.initials: J
authors.lastname: Kang
authors.affiliation: §Picobiology Institute, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Yanagisawa
authors.affiliation: §Picobiology Institute, Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Ogura
authors.affiliation: ⊥Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Masuda
authors.affiliation: ⊥Department of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ozawa
authors.affiliation: †Department of Emerging Materials Science, DGIST, Daegu 711-873, Korea.
authors.forename: Jaeheung
authors.initials: J
authors.lastname: Cho
mesh_terms: D006861:Hydrogen Peroxide / Q000737:chemistry; D047028:Macrocyclic Compounds / Q000737:chemistry; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D011789:Quantum Theory
chemical_list: D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D009532:Nickel; D006861:Hydrogen Peroxide