Structure dependence on redox state and charge in [Fe4(μ3-S4)(η-C5H5)4]m[M(mnt)2]n (M = Ni or Pt, m, n = 1 or 2)

Abstract

The complex salts [Fe₄(μ₃-S)₄(η-C₅H₅)₄]_m[M(mnt)₂]_n {M = Ni, n = 2, m = 1 1; n = 1, m = 1 2 or 2 3: M = Pt, n = 2, m = 1 4; n = 1, m = 1 5 or 2 6; mnt = S₂C₂(CN)₂} have been synthesized by stoichiometric reactions between [NEt₄]_n[M(mnt)₂] (n = 1 or 2, M = Ni or Pt) and [Fe₄(μ₃-S)₄(η-C₅H₅)₄][PF₆]_n (n = 1 or 2); the salts 2–6 have been structurally characterised. The molecular structures of the [Fe₄(μ₃-S)₄(η-C₅H₅)₄]^z+ (z = 1 or 2) cations and the [M(mnt)₂]^z− (M = Ni or Pt, z = 1 or 2) anions show mean Fe⋯Fe and M–S distances characteristic of z. The isostructural salts [Fe₄(μ₃-S)₄(η-C₅H₅)₄]₂[M(mnt)₂] (M = Ni 3 or Pt 6) comprise two monocations and one dianion; the planar anions, which form a ruffled ribbon arrangement, are interleaved by the near-spherical cations. The structure of [Fe₄(μ₃-S)₄(η-C₅H₅)₄][Pt(mnt)₂]₂, 4, with two monoanions and one dication, has face-to-face metal–metal pairs of [Pt(mnt)₂]⁻ ions separated by individual [Pt(mnt)₂]⁻ units, leading to anion layers interleaved by layers of cations. Salts 2 and 5 have very different structures. The nickel complex [Fe₄(μ₃-S)₄(η-C₅H₅)₄][Ni(mnt)₂] 2 comprises dications and dianions whereas the platinum complex [Fe₄(μ₃-S)₄(η-C₅H₅)₄][Pt(mnt)₂] 5 has monocations and monoanions. In salt 2 the dianions are well separated while in 5 the monoanions are weakly dimerised.