167867-87-0Relevant academic research and scientific papers
Structures, Electronic Properties, and Oxidation-Reduction Reactivity of Halogenated Iron Porphyrins
Grinstaff, Mark W.,Hill, Michael G.,Birnbaum, Eva R.,Schaefer, William P.,Labinger, Jay A.,Gray, Harry B.
, p. 4896 - 4902 (1995)
Molecular structures of both Fe(III)(TFPPBr8)Cl and Fe(II)(TFPPBr8)(py)2 porphyrins reveal saddle distortions: Fe(III)(TFPPBr8)Cl in triclinic space group P1-, a = 13.649(4) ?, b = 14.474(4) ?, c = 14.537 ?, α = 89.26(2)°, β = 67.13(1)°, γ = 71.82(2)°, V= 2494.3(13) ?**3, Z= 2; Fe(II)(TFPPBr8)(py)2 in triclinic space group P1-, a = 12.459(7) ?, b = 13.125(8) ?, c = 20.989(11) ?, α = 84.72(5)°, β = 72.87(4)°, γ = 69.04(5)°, V = 3063(3) ?**3, Z = 2. Similar to other chloro-iron(III) porphyrins, μeff at room temperature (5.96 μB) is that of a (6)A1 state; μeff at 2 K (4.2 μB) indicates a large zero-field splitting. The Soret bands of both Fe(III)(TFPPBr8)Cl and Fe(II)(TFPPBr8)(py)2 are red-shifted by approximately 23 nm relative to those of corresponding planar Fe(III) porphyrins. The metal and porphyrin reduction potentials of Fe(III)(TFPPBr8)Cl and Fe(II)(TFPPBr8)(py)2 are anodically shifted more than 400 mV from those of Fe(III)(TPP)Cl. Although[Fe(II)(TFPPBr8)Cl](1-) reacts very slowly with dioxygen, it is oxidized rapidly by tert-butyl hydroperoxide (TBHP); these Fe(II) reactivity properties taken together with the finding that the corresponding Fe(III) complex is reduced rapidly by TBHP provide strong support for the proposal that Fe(III)(TFPPBr8)Cl/O2-catalyzed alkane oxygenations occur by a radical chain mechanism in which alkyl hydroperoxide intermediates are decomposed efficiently by both Fe(III) and Fe(II) species.
(19)F NMR Spectra and Structure of Halogenated Porphyrins
Birnbaum, Eva R.,Hodge, Julia A.,Grinstaff, Mark W.,Schaefer, William P.,Henling, Lawrence,et al.
, p. 3625 - 3632 (2008/10/08)
Fluorine-19 NMR spectra of a series of halogenated porphyrins have beenused to create a spectral library of different types of fluorine splitting patterns for tetrakis(pentafluorophenyl) porphyrins (TFPP) complexed with diamagnetic and paramagnetic metal ions. The paramagnetic shift, line broadening, and fine structure of the resonances from the peripheral pentafluorophenyl rings are dependent on the symmetry and core environment of the porphyrin macrocycles. In combination with crystal structuredata, (19)F NMR helps define the behavior of halogenated porphyrins in solution. Six new crystal structures for TFPP and octahalo-TFPP derivatives are reported: H2TFPP in rhombohedral space group R3-, a = 20.327(4) ?, c = 24.368(5) ?, V = 8720(3) ?**3, Z = 9; ZnTFPP in monoclinic space group P21/C, a = 12.653(4) ?, b = 11.883(5) ?, c = 15.261(2) ?, β = 103.87(2)°, V = 2227.6(13) ?**3, Z =2; CuTFPP in rhombohedral space group R3-, a = 20.358(5), c = 24.347(6)?, V = 8739(4) ?**3, Z = 9; H2TFPPCl8 in triclinic space group P1-, a = 11.066(1) ?, b = 14.641(3) ?, c = 14.678(2) ?, α = 88.97(1)°, β = 76.05(1)°, γ = 71.29(1)°, V = 2181.4(6) ?**3, Z = 2; ZnTFPPCl8 in tetragonal space groupP4-21C, a = 19.502(20), c = 10.916(8) ?, V = 4152(6) ?**3, Z = 2; H2TFPPBr8 in monoclinic space group C2, a = 27.634(6) ?, b = 6.926(2) ?, c = 14.844(3) ?, β = 109.64(2)°, V = 2675.8(11) ?**3, Z = 2.
