Thioantimonate(III) anions acting as bridging ligands in neutral transition metal complexes: solvothermal synthesis and characterisation of the two novel compounds [Co(C6H18N4)]2Sb4S8 and [Co(C6H18N4)]2Sb2S5 containing [Sb4S8]4− and [Sb2S5]4− anions

Abstract

The two novel thioantimonate(III) compounds [Co(C₆H₁₈N₄)]₂Sb₄S₈1 and [Co(C₆H₁₈N₄)]₂Sb₂S₅2 were synthesised under solvothermal conditions by reacting elemental Co, Sb and S in a 95% solution of tris(2-aminoethyl)amine (tren). Compound 1 crystallises in the monoclinic space group P2₁/c, a = 17.936(4) Å, b = 13.442(3) Å, c = 14.000(3) Å, β = 101.73(3)°, and compound 2 crystallises in the monoclinic space group C2/c, a = 30.157(6) Å, b = 7.720(2) Å, c = 22.875(8) Å, β = 94.68(3)°. The [Sb₄S₈]⁴⁻ anion in compound 1 is composed of two SbS₃ and two SbS₄ units. The two SbS₄ moieties share a common edge and each SbS₄ has a common edge with a SbS₃ pyramid. This interconnection leads to the formation of three Sb₂S₂ heterorings. The two remaining terminal S atoms of the anion are bound in a monodentate fashion to the [Co(C₆H₁₈N₄)]²⁺ cation. The [Sb₂S₅]⁴⁻ anion in 2 is formed by two corner linked SbS₃ units. Two terminal S atoms are bound to the [Co(C₆H₁₈N₄)]²⁺ cation in a monodentate manner. Compounds 1 and 2 are the first compounds that contain thioantimonate(III) anions acting as bridging ligands. Both compounds start to decompose at about 240 °C due to the removal of the organic ligands. In the X-ray powder patterns of the decomposition products Sb₂S₃, CoSbS and CoS could be identified.