Solvothermal Syntheses, Crystal Structures and Properties of Thiomolybdates with Complex Transition Metal Cations

Abstract

Abstract The new compounds Ni2(tren)3(MO₂O2S6)2 · 2.75 H2O (I) and CO₂(tren)3(MoS4)2 (II) (tren = tris(2-aminoethyl)amine) were prepared under solvothermal conditions. The structure of I is built up of one-dimensional [Ni2(tren)3]n 4+ chains and isolated [MO₂O2S6]2-anions. Each Ni atom in the cationic chain is surrounded by six N-atoms to form a distorted octahedron. The connection of the Ni-atoms in the [Ni2(tren)3]n 4+ -units with the tren molecules leads to zigzag chains in the (100) plane. The situation is different for compound II which consists of isolated [CO₂(tren)3]4+ cations and discrete tetrahedral [MOS4]2-anions. The Co atom in the cation is in a distorted trigonal bipyramidal environment of four N atoms of one tren molecule and of one N atom from a bridging tren-molecule, building up the dimeric structure of the [CO₂(tren)3]4+ unit. Between the anions and cations of both compounds hydrogen bonding is observed. The thermal behaviour of I and II was investigated using differential thermoanalysis and thermogravimetry. On heating I first looses the crystal water and then decomposes slowly in one step, whereas II decomposes also in one step, but at a significantly lower temperature.