Solvothermal syntheses, crystal structures, and thermal stability of two new thioantimonates(III) using complex transition metal cations as structure directing agents:: the layered compound [Ni(dien)2]Sb4S7•H2O and the three-dimensional compound [Ni(dien)2]3Sb12S21•H2O

The two new thioantimonates(III) [Ni(dien)(2)]Sb4S7 . H2O (1) and [Ni(dien)(2)](3)Sb12S21 . H2O (11) were prepared under solvothermal conditions using elemental Ni, Sb, S and an aqueous solution of diethylenetriamine (dien) as solvent. Compound I crystallizes in the monoclinic space group P2(1)/c, a = 9.603(2) Angstrom, b = 16.137(3) Angstrom, c = 17.272(4) Angstrom, beta = 91.68(3)degrees, V = 2675.3(9) Angstrom(3), Z = 4 and compound 11 crystallizes in the monoclinic space group C2/c with a = 12.6072(7) Angstrom, b = 14.9967(7) Angstrom, c = 41.445(2) Angstrom, beta = 95.371(6)degrees, V = 7801.4(7) Angstrom(3), Z = 4. The two-dimensional (2)(infinity)[Sb4S72-] anion in I is composed of two SbS3 trigonal pyramids and two SbS4 units. The SbS3 units are connected via one corner to form a Sb2S5 unit and the two SbS4 moieties share a common edge building a trans-Sb2S6 unit. The Sb2S5 and trans-Sb2S6 units have one common S atom to form the layered (2)(infinity)[Sb4S72-] anion. Within the layers Sb2S2, Sb4S4 and Sb8S8 heterorings are found with the mer-[Ni(dien)(2)](2+) residing above and below the large pores. In compound 11 the (3)(infinity)[Sb12S216-] anion is composed of four SbS3 pyramids and two SbS4 units. The condensation of the different primary units yields SbxSx rings with x = 2, 3, 4, 8, and 32. The largest ring consists of 64 atoms (Sb32S32) and the pores with an ellipsoidal shape are oriented parallel to the [110] direction. To the best of our knowledge this is the largest SbxSx heteroring found in thioantimonates(III) so far. The cations are located above and below the large ring or within the plane of the ring. Nearly rectangular channels are running along [101] which have dimensions of about 7.6.13.5 Angstrom. The channels are occupied by the water molecule and by the ligands pointing into the channels. The thermal behavior of the compounds was investigated using differential thermoanalysis (DTA), thermogravimetry (TG) and mass spectroscopy (MS) measurements. Upon heating decomposition of the compounds starts at T-onset = 235degreesC (1) and T-onset = 258degreesC (11). The degradation of the samples proceeds in several steps and the ligands and water molecules are successively emitted. In the X-ray powder patterns of the decomposition products NiS, NiSbS, and Sb2S3 could be identified. (C) 2003 Elsevier Inc. All rights reserved.