A triclinic polymorph of bis­(μ(2)-ethane­thiol­ato)-1:2κ(2) S:S;3:4κ(2) S:S-(μ(4)-disulfido-1:2:3:4κ(4) S:S:S′:S′)tetra­kis­[tricarbonyl­iron(II)](2 Fe—Fe)

Next to the monoclinic polymorph [Cheng et al. (2005 ▶). Acta Cryst. E61, m892–m894], the triclinic title compound, [Fe(4)(C(2)H(5)S)(2)(S(2))(CO)(12)], is the second known form of this composition. The structure is composed of an [Fe(2)(C(2)H(5)S)(S)(CO)(6)] subcluster, which is linked to its counterpart by an inversion centre located at the mid-point of the central disulfide bond. The Fe(2)S(2) core of each subcluster exhibits a butterfly-like shape, with two S atoms bridging two Fe atoms. In the subcluster, each Fe atom is coordinated in a distorted octa­hedral coordination by three terminal carbonyl C atoms, two S atoms and one Fe atom. The crystal packing is accomplished through van der Waals inter­actions.