Improved syntheses of tetrachlorodi-.mu.-sulfidodiferrate(2-) ([Fe2S2Cl4]2-) and hexachloro-.mu.-oxodiferrate(2-) ([Fe2OCl6]2-) and oxo/sulfido ligand substitution by use of silylsulfide reagents

Abstract

New syntheses of [Fe2S2Cl4]2" (1) and [Fe2OCl6]2" (2) and terminal oxo/sulfido ligand substitution reactions have been devised with use of the reagents (Me3Si)2S (3), NaSSiMe3 (4), and NaOSiMe3 (5) in acetonitrile solutions. The preparation of 4 is described. Reactions of (Et4N) [FeCl4] with equimolar quantities of 3, 4, and 5 in acetonitrile afford the Et4N+ salts of 1 (76%, 77%) and 2 (66%), respectively, in good yields. In THF (Et4N)2(l) was isolated in essentially quantitative yield from a reaction using 3. Equimolar amounts of 2 and 3 give partial conversion to 1 in a bridge oxo/sulfido substitution reaction; a competing reaction is that of product Me3SiCl with 2 to form [FeCl4]~. The chelate complex VO(acen) reacts with excess 3 to give a quantitative in situ yield of VS(acen). On a preparative scale a 79% yield was obtained. Similarly, NbO(S2CNEt2)3 was converted to yellow NbS(S2CNEt2)3 (vNbs = 493 cm"1) in 52% isolated yield. These syntheses of 1 and 2 in particular offer advantages over previous methods. The results presented suggest that silylsulfide reagents may have extended utility in effecting bridging and terminal oxo/sulfido transformations. Physical Measurements. Electronic spectra were recorded on a Cary Model 219 spectrophotometer.

N‐Coordinated [2Fe–2S] and [4Fe–4S] Clusters: Synthesis, Structures and Spectroscopic Characterisation

“…Alternatively, CH 2 Cl 2 was dried with molecular sieves by using an MBraun SPS. (NEt 4 ) 2 [Fe 2 S 2 Cl 4 ] [18] (1) and (NEt 4 ) 2 [Fe 4 S 4 Cl 4 ] [19] (4) were synthesised according to literature procedures. 1 H NMR spectra were recorded with a Bruker Avance 500 MHz spectrometer.…”

“…Since the use of suitably substituted heterocycles was expected to favour crystallisation, 2-methylindole was chosen as a ligand for [2Fe-2S] cluster synthesis. Standard salt metathesis using 2methylindole, nBuLi and (NEt 4 ) 2 [Fe 2 S 2 Cl 4 ] (1) [18] led to the formation of a cluster product as indicated by typical resonances in the 1 H NMR spectrum, but (NEt 4 ) 2 [Fe 2 S 2 (2methylindolate) 4 ] (2) could not be isolated by crystallisation. Instead, colour changes and gradual precipitation of amorphous sticky material suggested gradual decomposition of the initial product in MeCN or dmf solution.…”

“…After stirring for 1 h, (NEt 4 ) 2 [Fe 2 S 2 Cl 4 ] [18] (1, 580 mg, 1.0 mmol) was added followed by a small amount of MeCN (10 mL). After stirring for a further 1 h, a brown solid was filtered off and washed with Et 2 O (20 mL).…”

Oxidized and reduced [2Fe–2S] clusters from an iron(I) synthon

“…Synthetic clusters help to elucidate how simpler ligands influence the reduction potentials and spectroscopic signatures, enabling the confident correlation of structure, spectroscopy, and behavior [16,17,18,19]. Traditionally, [2Fe-2S] clusters have been synthesized in two ways: cluster assembly or ligand exchange [8,20,21,22]. Cluster assembly entails the reaction between an iron(III) salt, a bidentate thiolate and NaSH.…”

The Complete Characterization of a Reduced Biomimetic [2 Fe‐2 S] Cluster

“…Two reversible one-electron reduction processes are assigned to the formation of the mixed-valent species at E 1/2 = À1.14 V and the all-ferrous species at E 1/2 = À2. 10 [11] The large separation between the two halfwave potentials revealed significant stabilization of the mixed-valent species 2 (K c = 1.7 10 16 ), a fact that allowed the chemical reduction of 1 (using decamethylcobaltocene) and isolation of 2, which proved to be stable in the solid state under nitrogen even at room temperature for several hours.…”