Search

The cyanomethane adduct of NbCl4 analyses for NbCl4·3CH3CN (1). A crystal-structure determination of this species shows that it contains cis octahedral [NbCl4(NCMe)2] and a solvent CH3CN molecule. The unique bond lengths are Nb–N 2.220(13)A and Nb–Cl 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 group Pnma. A total of 729 reflections above background have been collected on a diffractometer and refined to R 0.051.When the cyanomethane adducts of NbX4(X = Cl or Br) are treated with Sb2S3 in cyanomethane, adducts of NbX2S (X = Cl or Br) are formed. The products contain [{NbX2S(NCMe)2}2] in which there is a [graphic omitted] ring. The crystal structures of two compounds, (2) and (3), containing the [{NbCl2S(NCMe)2}2] dimeric unit have been determined. In (2) there are two molecules of occluded CH3CN for each dimer while (3) has one. Both (2) and (3) are triclinic with space group P, with (2) having a= 9.031 (7), b= 9.367(6), c= 8.360(8)A, α= 108.72(9), β= 94.93(7), γ= 105.70(8)°, Z= 1 and (3) having a= 14.965(18), b= 8.838(17), c= 9.543(23)A, α= 112.42(18), β= 84.39(28), γ= 103.65(21)°, Z= 2. For (2), 1 434, and for (3), 1 530, independent reflections above background have been collected on a diffractometer and refined to R 0.056 and 0.050 respectively.The dimer configurations in (2) and (3) are identical. The niobium atoms are in a pseudo-octahedral environment consisting of two cis sulphur [Nb–S 2.338(8)–2.349(7)A], two trans chlorine [Nb–Cl 2.383(6)–2.403(5)A], and two cis nitrogen atoms [Nb–N 2.286(26)–2.334(22)A]. In addition, in each dimer there is a Nb–Nb single bond [2.862(2)–2.872(3)A].