A new type of zinc sulfide cluster: [Zn10S7(py)9(SO4)3]·3H2O

Abstract

The cluster [Zn₁₀S₇(py)₉(SO₄)₃]·3H₂O has been synthesized by reaction of the product of thermolysis of [NMe₄]₄[Zn₁₀S₄(SPh)₁₆] [believed to be Zn₁₀S₄(SPh)₁₂] with pyridine containing Na₂SO₄. The compound was characterised by X-ray crystallography: monoclinic space group P2₁/c, a = 11.279(6), b = 23.419(6), c = 27.26(1) Å, β = 107.74(2), Z = 4. This cluster is unprecedented in its architecture, and for its combination of sulfide, sulfate and pyridine ligands. It has pseudo-three-fold symmetry. In the core the ten Zn atoms are arrayed as a central Zn₄ tetrahedron on the three-fold axis, crowned with a slightly puckered Zn₆ hexagon around the axial Zn atom of the Zn₄ tetrahedron. The Zn₄ tetrahedron contains µ₄-S^2–. The axial Zn atom of the Zn₄ tetrahedron is connected to the Zn₆ hexagon through three µ₃-S^2– ligands. Another three µ₃-S^2– ligands connect the base of the Zn₄ tetrahedron to the Zn₆ hexagon. Each SO₄^2– ion bridges three Zn atoms: two from an edge of the hexagon and one basal Zn atom of the tetrahedron. All Zn atoms have distorted tetrahedral co-ordination, completed by terminal pyridine ligands on all except the axial Zn atom. The crystal supramolecularity is a stacking of the clusters such that three axially directed pyridine ligands (on the basal Zn₄ atoms) nestle amongst six equatorially directed pyridine ligands (on the Zn₆ hexagon) of an adjacent molecule. Water molecules are hydrogen bonded to SO₄^2– and µ₃-S atoms. The Zn–S connectivity in this cluster is different from that in the cubic or hexagonal lattices of ZnS, and from that in known M₈S(SR)₁₆, M₁₇S₄(SR)₂₈ and M₁₀(SR)₁₀ clusters formed by Group 12 metals.