Synthesis, structural characterization and conversion of dinuclear iron–sulfur clusters containing the disulfide ligand: [Cp*Fe(μ–η2:η2-bdt)(cis-μ–η1:η1-S2)FeCp*], [Cp*Fe(μ-S(C6H4S2))(cis-μ–η1:η1-S2)FeCp*], and [{Cp*Fe(bdt)}2(trans-μ–η1:η1-S2)]

Abstract

The treatment of [Cp*Fe(μ–η²:η⁴-bdt)FeCp*] (1, Cp* = η⁵-C₅Me₅, bdt = benzene-1,2-dithiolate) with 1/4 equiv. of elemental sulfur (S₈) gave a dinuclear iron–sulfur cluster [Cp*Fe(μ–η²:η²-bdt)(cis-μ–η¹:η¹-S₂)FeCp*] (2), which contains a cis-1,2-disulfide ligand. When complex 2 further interacted with 1/8 equiv. of S₈, another sulfur atom inserted into an Fe–S bond to give a rare product [Cp*Fe(μ-S(C₆H₄S₂))(cis-μ–η¹:η¹-S₂)FeCp*] (3). Unexpectedly, a trans-1,2 disulfide-bridged diiron complex [{Cp*Fe(bdt)}₂(trans-μ–η¹:η¹-S₂)] (4) was isolated from the reaction of complex 1 with 1/2 equiv. of S₈, which represents a structural isomer of [2Fe–2S] ferredoxin-type clusters. In addition, cis-1,2-disulfide-bridged complex 3 can slowly convert into trans-1,2-disulfide-bridged complex 4 and the complex [Cp*Fe(μ–η²:η²-S₂)(cis-μ–η¹:η¹-S₂)FeCp*] (5) by self-assembly reaction at ambient temperature, which is evidenced by time-dependent ¹H NMR spectroscopy.