Hydrosulfide Ligation of an Iron(II) Porphyrinate
Jeffrey W. Pavlik, Bruce C. Noll and W. Robert Scheidt
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556
Hydrogen sulfide has been recently recoginized, along with CO and NO as a gasotransmitter.1,2 The response of vertebrate tissues to doses of H2S is quite similar to a hypoxic response.2 Hemoglobin–sulfide binding is reported in a limited number of invertebrates.3,4 Because signaling may involve sulfur bound hemes, H2S and HS– iron porphyrinates are of considerable interest. We report a synthesis and characterization of hydrosulfido–(octaethylporphyrinato)iron(II). An X–ray crystal structure revealed two unique five coordinate porphyrins per asymmetric unit, [Na(222)]2[Fe(OEP)(HS)]2·C6H6. Iron out-of-plane distances were 0.70Å and 0.64Å, and a mean dFe–Np of 2.11Å is consistent with high-spin iron(II). Dilution of the sample resulted in dissociation of HS– so additional ligand was supplied to analyze the complex in solution. A Soret band was observed at 396 nm and a Q–band absorption was at 555 nm. An infrared spectrum was taken from a CsI pellet, and the sample absorbed at 344 cm-1. This absorption is consistent with an iron-sulfur stretch, and the peak was absent after exposure of the pellet to air. The mass spectrum had a peak at m/z=621.3, consistent with the [Fe(OEP)(HS)]− ion.
References and Notes
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(3) Numoto, N; Nakagawa, T.; Kita, A.; Sasayama, Y.; Fukumori, Y.; Miki, K. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 14521.
(4) Rizzi, M.; Wittenberg, J. B.; Coda, A.; Ascenzi, P.; Bolognesi, M. J. Mol. Biol. 1996,
258, 1.