72186-60-8Relevant academic research and scientific papers
Synthesis, characterization, and binding affinity of hydrosulfide complexes of synthetic iron(II) porphyrinates
Meininger, Daniel J.,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 142 - 149 (2016/12/26)
The binding and reactivity of the hydrosulfide ion (HS?) to iron(II) porphyrinates has been examined for several synthetic meso-tetraphenylporphine (TPP) derivatives. In all cases, HS? coordinates to the iron centers in a 1:1 stoichiometry with formation constants (Kf) that reflect the electronic characteristics of the porphyrinate ligands. In the case of the F8TPP ligand (F8TPP?=?dianion of 5,10,15,20-tetrakis(2,6-difluorophenyl)porphine), an intermediate complex proposed as the hydrosulfide bridged dimer, (Bu4N)[Fe2(μ-SH)(F8TPP)2], was identified by NMR spectroscopy en route to formation of (Bu4N)[Fe(SH)(F8TPP)]. A robust procedure is reported for the synthesis and isolation of the parent hydrosulfide adduct, (Bu4N)[Fe(SH)(TPP)], which has permitted a detailed examination of its spectroscopy and chemical reactivity. Electrochemical measurements demonstrate that [Fe(SH)(TPP)]? is oxidized reversibly at a potential of ??0.832?V (vs ferrocene/ferrocenium) consistent with other iron porphyrinates containing sulfur-based ligands. Despite this fact, chemical oxidation of (Bu4N)[Fe(SH)(TPP)] with ferrocenium tetrafluoroborate produced only [Fe(TPP)] indicating that the putative iron(III) hydrosulfide adduct, [Fe(SH)(TPP)], decomposes rapidly. Treatment of (Bu4N)[Fe(SH)(TPP)] with other biologically relevant molecules such as NO and 1,2-dimethylimidazole resulted in simple displacement of the HS? ligand as governed by the relative Kf values of the added ligands. The solid-state structure of one hydrosulfide adduct, (Bu4N)[Fe(SH)(F8TPP)], was determined by X-ray crystallography and found to display the expected five-coordinate geometry about iron with an Fe-S distance of 2.323(1) ?. The relevance of the hydrosulfide chemistry with synthetic iron porphyrinates is discussed in terms of the possible reactivity for H2S and its derivatives at heme sites in biology.
Electronic configuration assignment and the importance of low-lying excited states in high-spin imidazole-ligated iron(II) porphyrinates
Hu, Chuanjiang,Roth, Arne,Ellison, Mary K.,An, Jin,Ellis, Christina M.,Schulz, Charles E.,Scheidt, W. Robert
, p. 5675 - 5688 (2007/10/03)
The synthesis and characterization of six new high-spin deoxymyoglobin models (imidazole-(tetraarylporphyrinato)iron(II)) are described. These have been intensively studied by temperature-dependent Moessbauer spectroscopy from 295 to 4.2 K. All complexes
Ligand, Oxygen, and Carbon Monoxide Affinities of Iron(II) Modified Capped Porphyrins
Hashimoto, Toshiaki,Dyer, Robert L.,Crossley, Maxwell J.,Baldwin, Jack E.,Basolo, Fred
, p. 2101 - 2109 (2007/10/02)
Ligand, O2, and CO binding constants are presented for iron(II) modified capped porphyrins.Steric effects at the axial position outside the cap were altered by changing a tetraphenyl-type cap to a corresponding tetranaphthalene-type cap.The steric hindrance caused by the peri hydrogens of the naphthalene groups is believed to be responsible for the decrease in ligation in the order n-propylamine > isobutylamine > sec-butylamine > tert-butylamine.Inductive effects in the porphyrin plane were altered by introducing a nitro group.Such an electron-withdrawing group enhances ligation but retards oxygenation.The solvent effect on O2 binding by capped complexes is small, presumably because the environment of the O2 bound inside the cap is not greatly changed by changes in solvent.The CO affinities of iron(II) capped porphyrins and of corresponding iron(II) flat-open porphyrins are similar.In contrast, the O2 affinities of the capped systems are lower than their flat-open counterparts, which means the iron(II) capped porphyrin complexes discriminate against O2 but not CO.This is discussed in terms of distal steric effects on the stable structures of Fe-O-O (bent) and Fe-C-O (linear).
