One-dimensional magnetism in [Ta_6Cl_12(CH_3OH)_6]BR_3 and [(TA_6Cl_12)Cl(H_2O)_5][CdBr_4]&middot ; ; 6H_2O with possible merohedral twinning in the latter

Low-dimensional antiferromagnetic behaviour is observed for a number of compounds with paramagnetic hexanuclear tantalum halide clusters. Among others it has been observed for [Ta_6Cl_12(CH_3OH)_6]Br_3 (1) and [(Ta_6Cl_12)Cl(H_2O)_5][CdBr_4]&middot ; ; 6H_2O (2). The compound 1 crystallizes in the R-3 space group, a = b = 19.127(4) &Aring ; ; , c = 8.565(1) &Aring ; ; and the compound 2 in the Fd-3m space group, a = 19.974(1) &Aring ; ; . One-dimensional packing motifs in both structures are suggested for the explanation of the observed low-dimensional magnetism.