The hydrothermal synthesis, crystal structures and thermal stability of the novel one- and two-dimensional thioantimonate(III) compounds [Co(tren)]Sb2S4 and [Ni(tren)]Sb2S4

Two novel thioantimonate(IH) compounds [Co(C6H18N4)]-Sb2S4 (1) and [Ni(C6H1 8N4)]Sb2S4 (2) were synthesised under solvothermal conditions by reacting t he transition metal, Sb and S in a 50% solution of tris(2-aminoethyl)amine (tren). The use of a tetradentate amine yields incompletely shielded transi tion metal cations which in turn are able to form bonds to the sulfur atoms of thioantimonate(IH) anions. Compound 1 crystallises in the orthorhombic space group Pbca, a = 13.886(3) Angstrom, b = 11.452(2) Angstrom, c = 20.54 9(4) Angstrom, V = 3268(1) Angstrom (3), Z = 8 and compound 2 crystallises in the monoclinic space group P2(1)/n, a = 6.906(1) Angstrom, b = 22.822(5) Angstrom, c = 10.347(2) Angstrom, beta = 103.17(3)degrees, V = 1587.9(6) A ngstrom (3), Z = 4. The (2)(proportional to)[Sb2S42-] anion in compound 1 i s formed by an SbS3 and an SbS4 unit sharing a common corner. Two SbS4 unit s have a common edge to form an Sb2S2 heterocycle. Four such Sb2S2 rings ar e at the corners of a two-dimensional square-like net. Interconnection of t he rings by SbS3 pyramids yields Sb10S10 rings with pores measuring 10 .8.4 Angstrom in diameter. The pores are filled by the [Co(tren)](2+) cations. The [Co](2+) cation is in a trigonal bipyramidal environment of four N atom s of the tren ligand and one S atom of the SbS3 pyramid. The one-dimensiona l (1)(proportional to)[Sb2S42-] chain anion in 2 is built by two corner-sha ring SbS3 units. The [Ni](2+) cation is in an octahedral environment consis ting of four N atoms of the tren ligand and two S atoms of the anion. An Ni Sb2S3 heteroring in a twist conformation is formed with an unusually large Ni-S(1)-Sb(1) angle of 121.73(3)degrees. For the [Co](2+) (d(7)) cation no significant energy differences can be expected for the trigonal bipyramidal and octahedral coordination, and due to the geometrical requirements of th e tetradentate ligand the former environment is preferred. In contrast, for [Ni](2+) (d(8)) an octahedral environment is energetically favoured over t he trigonal bipyramidal arrangement. Both compounds start to decompose unde r an Ar atmosphere at about 250 degreesC. For 1 two not well resolved steps are observed, whereas 2 decomposes in one step. In the X-ray powder patter ns of the grey products Sb2S3, Co/NiSbS and Co/NiS could be identified.