Reaction of O2 with a high-spin mononuclear iron(II) complex supported by a five-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species, which was characterized by UV/Vis spectroscopy and resonance Raman spectroscopy. (1)H NMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with H-atom donating reagents to give a low-spin iron(III)-hydroperoxo species showing characteristic UV/Vis, resonance Raman, and EPR spectra.

3-Difluoromethylated 2,3-dihydrobenzoheteroles, 2,3-dihydrobenzofurans, 2,3-dihydrobenzothiophenes, and indolines were readily synthesized from ortho-heterosubstituted bromobenzenes, 2-bromophenols, 2-bromobenzenethiols, and 2-bromoanilines, respectively, in two steps: (1) γ-selective allylic substitution of 3-bromo-3,3-difluoropropene with heteronucleophiles and (2) intramolecular radical cyclization of the resulting 3,3-difluoroallylic compounds.

Reaction of O 2 with ah igh-spin mononuclear iron(II) complex supported by af ive-azole donor set yields the corresponding mononuclear non-heme iron(III)-superoxo species,w hich was characterized by UV/Vis spectroscopya nd resonance Raman spectroscopy.1 HNMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low-spin iron(III) and superoxide. This superoxo species reacts with Hatom donating reagents to give al ow-spin iron(III)-hydroperoxo species showing characteristic UV/Vis,r esonance Raman, and EPR spectra.

The effects of the substituents on the chelating ligands located in the secondary coordination sphere on the O2 affinity of cobalt­(II) centers have been explored. The combination of facially capping tridentate tris­(pyrazolyl)­borates (= TpMe2,4R) and bidentate bis­(imidazolyl)­borates (= [B­(Im N‑Me)2MeX]− ; LX) yields square-pyramidal cobalt­(II) complexes. The structural properties of the substituent groups X attached to the boron center of LX affect the arrangement of X in the resulting cobalt­(II) complexes [CoII(TpMe2,4R)­(LX)]. When the boron-attached moiety of X is a relatively bulky sp3-CH2Y group (i.e., X:Y = Me:H and nBu:nPr), the alkyl group X faces the cobalt center, whereas for isopropoxy (OiPr) and phenyl (Ph) groups, of which the boron-attached atoms are a less hindered oxygen atom and a planer sp2-carbon, respectively, the X group is arranged away from the cobalt center. This flexible behavior of LX is reflected in the O2 affinity of the cobalt­(II) center, which depends on the extent to which the complex sphere is shielded by the ligands. The dependence of the cobalt­(II) oxidation potential on the X substituent of LX is inconsistent with the O2 affinity. On the other hand, the electronic properties of R, which is attached to the fourth position of the pyrazolyl rings in the rigid TpMe2,4R ligand, are reflected in the electrochemical properties and O2 affinity of the cobalt center.

Iron oxygenases mimicking active sites have been constructed on the solid support by anchoring a bis(imidazolyl)borate ligand to carboxylate-functionalized SBA-15 type mesoporous silica gels. Initial loading amounts of an organocarboxylic acid modifier on the silicates affect the hydrocarbon oxygenation catalyses with H2O2 due to changing of the structures of the surface metallocomplex active sites.