70622-46-7Relevant articles and documents
Naked five-coordinate FeIII(NO) porphyrin complexes: Vibrational and reactivity features
Lanucara, Francesco,Chiavarino, Barbara,Crestoni, Maria Elisa,Scuderi, Debora,Sinha, Rajeev K.,Maitre, Philippe,Fornarini, Simonetta
, p. 4445 - 4452 (2011/06/21)
Model ferric heme nitrosyl complexes, [Fe(TPP)(NO)]+ and [Fe(TPFPP)(NO)]+, where TPP is the dianion of 5,10,15,20-tetrakis- phenyl-porphyrin and TPFPP is the dianion of 5,10,15,20-tetrakis- pentafluorophenyl-porphyrin, have been obtained as isolated species by the gas phase reaction of NO with [FeIII(TPP)]+ and [Fe III (TPFPP)]+ ions delivered in the gas phase by electrospray ionization, respectively. The so-formed nitrosyl complexes have been characterized by vibrational spectroscopy also exploiting 15N-isotope substitution in the NO ligand. The characteristic NO stretching frequency is observed at 1825 and 1859 cm-1 for [Fe III(TPP)(NO)]+ and [FeIII(TPFPP)(NO)] + ions, respectively, providing reference values for genuine five-coordinate FeIII(NO) porphyrin complexes differing only for the presence of either phenyl or pentafluorophenyl substituents on the meso positions of the porphyrin ligand. The vibrational assignment is aided by hybrid density functional theory (DFT) calculations of geometry and electronic structure and frequency analysis which clearly support a singlet spin electronic state for both [Fe(TPP)(NO)]+ and [Fe(TPFPP)(NO)]+ complexes. Both TD-DFT and CASSCF calculations suggest that the singlet ground state is best described as FeII(NO+) and that the open-shell AFC bonding scheme contribute for a high-energy excited state. The kinetics of the NO addition reaction in the gas phase are faster for [Fe III(TPFPP)]+ ions by a relatively small factor, though highly reliable because of a direct comparative evaluation. The study was aimed at gaining vibrational and reactivity data on five-coordinate Fe III(NO) porphyrin complexes, typically transient species in solution, ultimately to provide insights into the nature of the Fe(NO) interaction in heme proteins.
Five- and Six-Coordinated Nitrosyl Iron(II) Complexes of Tetrakis (p-substituted phenyl)porphyrins. Substituent Effects on the EPR Parameters and the NO Stretching Frequencies
Yoshimura, Tetsuhiko
, p. 2819 - 2828 (2007/10/02)
Five- and six-coordinated nitrosyl iron(II) complexes of a series of tetrakis(p-substituted phenyl)porphyrins have been prepared.Their EPR and IR spectra have been measured and analyzed in order to elucidate the cis-effect of substitutens on the axial nitrosyl ligand.As the first redox potentials of the free base porphyrins in the complexes became positive, the NO stretching frequencies increased in both five-coordinated and six-coordinated nitrosyl(porphyrinato)iron(II) complexes with a nitrogenous base at an axial site trans to the NO group.The positive shift of the redox potentials led to an increase in the EPR g values and hyperfine coupling constants at room temperature and at 77 K for the five-coordinated complexes, while it led to a decrease in g values and to a slight increase in hyperfine coupling constants for the six-coordinated complexes.These results are rationalized by invoking that, as the electron-withdrawing power of porphyrin peripheral substituents is enhanced, the iron-to-NO bond in both the five- and six-coordinated complexes is weakened and the iron-to-nitrogenous base bond in the six-coordinated complexes is strengthened.The difference in the cis- and trans-effects on the EPR parameters and NO stretching frequencies is also discussed.
Electrochemical and spectroelectrochemical characterization of intermolecular nitrosyl transfer between iron and cobalt porphyrins
Mu,Kadish
, p. 1031 - 1036 (2008/10/08)
The transfer of a nitrosyl ligand between neutral and oxidized iron and cobalt metalloporphyrins in dichloromethane solutions was investigated by electrochemistry and FTIR or ESR spectroelectrochemistry. The transfer of NO from (P)Co(NO) to (P)Fe, from [(P)Co(NO)]+ to (P)FeClO4, and from [(P)Fe(NO)]+ to (P)Co was demonstrated for complexes where P = the dianion of tetraphenylporphyrin (TPP), meso-tetrakis(2,4,6-trimethylphenyl)porphyrin (TMP), or octaethylporphyrin (OEP). The driving force in these reactions is related to both the nature and oxidation state of the central metal in (P)M(NO) or [(P)M(NO)]+, where M = Fe or Co, and follows the order (P)Fe(NO) > (P)Co(NO) > [(P)Fe(NO)]+ > [(P)Co(NO)]+.
