93862-19-2Relevant academic research and scientific papers
Electrochemistry of (TMP)FeOH and (TMP)FeOCH3 in dichloromethane. Electrogeneration of iron(IV) and iron(II) porphyrins
Swistak,Mu,Kadish
, p. 4360 - 4366 (2008/10/08)
The electrochemistry of (TMP)FeOH, (TMP)FeOCH3, and (TMP)FeOR where TMP is the dianion of tetrakis(2,4,6-trimethylphenyl)porphyrin and OR- = OPh-, OCH2Ph-, or OCH(CH3)2- were investigated in methylene chloride. The reduction of (TMP)FeOCH3 or (TMP)FeOH in CH2Cl2, 0.1 M TBAP occurs via an initial quasi-reversible one-electron-transfer step at E1/2 = -0.86 V. A second reduction of [(TMP)FeOH]- or [(TMP)FeOCH3]- is not observed but reduction of (TMP)Fe is observed at E1/2 = -1.20 V after dissociation of the anionic ligand. The initial oxidations of (TMP)FeOH and (TMP)FeOCH3 occur at E1/2 = 0.98 V in CH2Cl2, 0.1 M TBAP to generate [(TMP)FeOCH3]+ and [(TMP)FeOH]+. These cationic species can be stabilized at low temperature, but at room temperature one or more chemical reactions occur to generate either (TMP)FeClO4 or (TMP)FeCl, both of which undergo two oxidations at ～ 1.1 and 1.5 V vs. SCE. Thin-layer spectroelectrochemistry was carried out at both room temperature and low temperature in order to characterize the products of each electrochemical and chemical reaction Steady-state voltammograms were also obtained at a microelectrode in CH2Cl2, 0.3 M TBAP and showed one reduction and two oxidations of (TMP)FeOH and (TMP)FeOCH3. All three processes had equal currents, consistent with the addition or abstraction of a single electron at E1/2 = -0.95, +1.00, and +1.50 V. The electrochemical and spectroelectrochemical data were combined to give a self-consistent mechanism for oxidation and reduction of the investigated complexes.
Preparation and Characterization of a Dialkoxyiron(IV) Porphyrin
Groves, John T.,Quinn, Robert,McMurry, Thomas J.,Nakamura, Mikio,Lang, George,Boso, Brian
, p. 354 - 360 (2007/10/02)
(Perchlorato)(tetramesitylporphyrinato)iron(III) was oxidized with ferric perchlorate to generate the corresponding iron(III) porphyrin cation radical, Fe(TMP)(ClO4)2 (1).The 1H NMR and visible spectra of 1 were similar to those of other bis(perchlorato)iron(III) porphyrin cation radicals.The reaction of 1 with 1 equiv of potassium iodide regenerated Fe(TMP)(ClO4).The treatment of 1 with 2 equiv of sodium methoxide in methanol produced a new species, 2, which was shown to be an iron(IV) complex.The β-pyrrole protons of 2 were found at very high field, -37.5 ppm relative to TMS at -78 deg C in CD2Cl2.All other resonances were observed near the expected diamagnetic positions.The temperature dependence of the β-pyrrole resonance displayed the characteristic Curie behaviour of an isolated paramagnet.The sharp singlet observed for the meta hydrogens of 2 suggested a structure with D4h symmetry.The coordination of methoxide in 2 was inferred from the requirement of 2 equiv of alkoxide to form them and the broadened 1H-methyl resonances, respectively.The oxidation of (TMP)FeIII(OCH3) with 1.2 equiv of iodosylmesitylene in methanol produced 2 and 0.7 equiv of free iodomesitylene.The Moessbauer spectra of 2 under conditions of variable temperature and variable magnetic field indicated a non-Kramers system with an isomer shift (δ) of -0.025 and a quadrupole splitting (ΔEQ) of 2.10.Magnetic susceptibility measurements on 2 gave a value of μβ=2.9, close to the spin-only value for two unpaired electrons.No EPR signals were detected for 2.Taken together the data support an S=1 iron(IV) porphyrin dimethoxide structure IV(TMP)(OCH3)2> for 2.
Iron(IV) Porphyrins from Iron(III) Porphyrin Cation Radicals
Groves, John T.,Quinn, Robert,McMurry, Thomas J.,Lang, George,Boso, Brian
, p. 1455 - 1456 (2007/10/02)
The preparation and spectroscopic data of FeTMP(ClO4)2 are reported; the reaction of (1) with NaOMe-MeOH gave a new red species, (2), which is indicated to exist (a) as a symmetrically ligated complex with a vacant dx2-y2 iron orbital (1H n.m.r.) and (b) in the iron(IV) state (Moessbauer spectroscopy).
