title: Hydrosulfide (HS-) coordination in iron porphyrinates.
abstract: Recent reports of potential physiological roles of hydrogen sulfide have prompted interest in heme-sulfide interactions. Heme-H(2)S and/or heme-HS(-) interactions could potentially occur during endogenous production, transport, signaling events, and catabolism of H(2)S. We have investigated the interaction of the hydrosulfide ion (HS(-)) with iron porphyrinates. UV-vis spectral studies show the formation of [Fe(Por)(SH)](-), [Fe(Por)(SH)(2)](2-), and the mixed-ligand species [Fe(Por)(Im)(SH)](-). UV-vis binding studies of [Fe(OEP)] and [Fe(T-p-OMePP)] (OEP = octaethylporphyrinate; T-p-OMePP = tetra-p-methoxyphenylporphyrinate) with HS(-) allowed for calculation of the formation constants and extinction coefficients of mono- and bis-HS(-) complexes. We report the synthesis of the first HS(-)-bound iron(II) porphyrin compounds, [Na(222)][Fe(OEP)(SH)].0.5C(6)H(6) and [Na(222)][Fe(T-p-OMePP)(SH)].C(6)H(5)Cl (222 = Kryptofix-222). Characterization by single-crystal X-ray analysis, mass spectrometry, and Mossbauer and IR spectroscopy is all consistent with that of known sulfur-bound high-spin iron(II) compounds. The Fe-S distances of 2.3929(5) and 2.3887(13) A are longer than all reported values of [Fe(II)(Por)(SR)](-) species. An analysis of the porphyrin nonplanarity for these derivatives and for all five-coordinate high-spin iron(II) porphyrinate derivatives with an axial anion ligand is presented. In our hands, attempts to synthesize iron(III) HS(-) derivatives led to iron(II) species.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Pavlik
authors.forename: Bruce C
authors.initials: BC
authors.lastname: Noll
authors.forename: Allen G
authors.initials: AG
authors.lastname: Oliver
authors.forename: Charles E
authors.initials: CE
authors.lastname: Schulz
authors.forename: W Robert
authors.initials: WR
authors.lastname: Scheidt
mesh_terms: D018360:Crystallography, X-Ray; D006862:Hydrogen Sulfide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D008665:Metalloporphyrins; D007501:Iron; D006862:Hydrogen Sulfide