Chemistry of [Fe6S6]3+ prismatic Cages. Synthesis, structural characterization, and electronic structures of the [Et4N]3[Fe6S6L6] Clusters (L = p-CH3C6H4O-, Br-)

Mercouri G Kanatzidis, A. Salifoglou, D. Coucouvanis

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Abstract

The syntheses of the [Cat]3[Fe6S6L6] clusters (L = Br-, cat = [Et3MeN]+; L = ArS-, Cat = [Et4N]+) are reported. The crystal and molecular structures of [Et4N]3[Fe6S6(p-CH3C 6H4O)6] (I) and of [Et4N]3[Fe6S6Br 6]·CH3CN (II) are described in detail. I and II crystallize in the monoclinic space groups P21/a and P21/n, respectively, with two molecules in the unit cell. The cell dimensions in I are a = 13.173 (5) Å, b = 19.848 (10) Å, c = 14.304 (4) Å, and β = 98.05 (3)°. In II, a = 14.531 (3) Å, b = 11.028 (2) Å, c = 17.566 (3) Å, and β = 100.69 (1)°. Intensity data for both I and II were collected with a four-circle computer-controlled diffractometer with use of the θ-2θ scan technique. Both structures were solved by conventional methods from 3461 and 2516 reflections for I and II, respectively. The structures were refined by full-matrix least-squares techniques (283 parameters for I and 213 parameters for II) to final R values of 0.075 and 0.049, respectively, for I and II. The anions in I and II contain the [Fe6S6]3+ hexagonal-prismatic core, which consists of alternating tetrahedral Fe and triply bridging S atoms. Three of the Fe coordination sites are occupied by core sulfide atoms while the fourth coordination site is filled by the terminal RO- and Br- ligands. There are two sets of Fe⋯Fe distances in the Fe6S6 cores with mean values of 2.761 (5), 2.749 (4) Å and 3.80 (4), 3.81 (2) Å, respectively, for I and II. Similarly, two sets of Fe-S-Fe angles are found for I and II at 74.6 (2) and 74.3 (1)° and 113.8 (2) and 114.2 (9)°. The Fe-S bonds in I and II are 2.276 (5) and 2.274 (4) Å. The Fe-O bond in I is 1.880 (11) Å, and the Fe-Br bond in II is 2.366 (9) Å. The reactivity, cyclic voltammetry, and isotropically shifted NMR spectra of I and II are discussed in detail.

Original languageEnglish
Pages (from-to)2460-2468
Number of pages9
JournalInorganic Chemistry
Volume25
Issue number14
Publication statusPublished - 1986

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ASJC Scopus subject areas

  • Inorganic Chemistry

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