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The isolation of a large range of thio-, seleno-, and 0x0-halides has been achieved by allowing Sb,Y, (Y = 0, S, or Se) to react with a metal halide a t room temperature with carbon disulphide as solvent. SEVERAL routes have been described for the preparation of the thio-and seleno-halides of the early transition metals.l-' The superior method is the reaction of a metal halide with either sulphur or Sb,S, as it is relatively easy to

The cyanomethane adduct of NbCI, analyses for NbC14.3CH,CN (1 ). A crystal-structure determination of this species shows that it contains cis octahedral [NbCI,(NCMe),] and a solvent CH,CN molecule. The unique bond lengths are Nb-N 2.220(13) A and Nb-CI 2.328(2), 2.343(6), and 2.349(4) A. The crystals of (1) are orthorhombic with unit-cell dimensions a = 10.437( 11), b = 13.883( 12), c = 9.828(9) A,Z = 4, and space groupPnma. A total of 729 reflections above background have been collected on a diffractometer and refined to R 0.051.When the cyanomethane adducts of NbX, (X = CI or Br) are treated with Sb2S, in cyanomethane, adducts of NbX,S (X = CI or Br) areformed. The products contain [{NbX,S(NCMe),},] in which there is a Nb-S-Nb-S ring. The crystal structures of two compounds, ( 2) and (3), containing the [{NbCI,S(NCMe),),] dimeric unit have been determined. In (2) there are two molecules of occluded CH&N for each dimer while (3) has one. Both'(2) and(3) are triclinic with space group P1, with (2) having a = 9.031 (7),

The conditions necessary for the synthesis of the two reported polymorphs of CuNb,O, from the binary oxides have been investigated. The black, orthorhombic phase has been prepared in a pure crystalline form and its single-crystal structure determined. It is isomorphous with the M"Nb,O, columbite system (orthorhombic, a = 14.019(11) A, b = 5.623(7) A, c = 5.107(7) A, space group Pbcn) but the CuO, octahedra display a large tetragonal distortion [Cu-0, 1.976(6) x 2, 1.973(6) x 2, and 2.383(6) x 2 A]. Above 225 K the compound is magnetically dilute and obeys the Curie law (peff= l.91pB), whereas Curie-Weiss behaviour was observed between 225 and 50 K (8= -30 K) with a maximum susceptibility at 20 K. The magnetic data have been analysed in terms of a onedimensional antiferromagnetic chain model.The yellowish-green, monoclinic phase is more difficult to prepare in a pure form than the black, orthorhombic phase. Some provisional details for its preparation are reported.