Paul Klingelhöfer

Pyridin-Addukte von Cyclothiazeno-Vanadiumdichlorid Die Kristallstruktur von [VCl2(N3S2)(C5H5N)] / Pyridine Adducts of Cyclo-thiazeno Vanadium Dichloride The Crystal Structure of [VCl2(N3S2)(C5H5N)]

Abstract The pyridine complexes of cyclo-thiazeno vanadium dichloride, [VCl2(N3S2)py] and [VCl2(N3S2)(py)2] were synthesized by reactions of polymeric VCl2(N3S2) with varying amounts of pyridine in CH2Cl2. The compounds were characterized by their IR spectra as well as by their 51V NM R spectra. The crystal structure of [VCl2(N3S2)(C5H5N)] was determined by means of X-ray diffraction (1582 independent observed reflexions, R = 0.031). Crystal data: orthorhombic, space group Pnma, a = 1372, b - 2261, c - 1068 pm, Z = 12. In the lattice there are two monomeric, crystallographically independent molecules [VCl2(N3S2)(C5H5N)], which differ only slightly. The vanadium atoms have a trigonal bipyramidal coordination with the N atom of the pyridine molecule and one chlorine atom in apical positions, and with one chlorine atom and the N atoms of the cyclo-thiazeno ligand in equatorial positions. The VN bond lengths of the planar VN3S2 ring of 174 pm correspond to double bonds

ReCl5 • OPCl3; IR-Spektrum und Kristallstruktur / ReCl5 • OPCl3; IR Spectrum and Crystal Structure

Single crystals of ReCl5 • OPCl3 were obtained by cooling a saturated solution of rheniumpentachloride in phosphorylchloride. It formes black needles, which are extremely sensitive to moisture. In the IR spectrum ν(PO) is shifted downwards by 140 cm-1 in comparison with liquid POCl3, indicating coordination via oxygen. The crystal structure was solved and refined from Xray diffraction data (space group Pnma, four formula units per unit cell, a = 1629, b = 790, c = 877 pm, 902 observed, independent reflexions, R = 0.040). The complex forms discrete molecules ReCl5 • OPCl3, with symmetry Cs(m). Bond lengths are Re -O - 214 pm and P-O = 146 pm, the angle Re -O -P is 143°

β-NbBr5, eine neue Modifikation von Niobpentabromid mit einer eindimensionalen Lagenfehlordnung/ β-NbBr5, a New Modification of Niobium Pentabromide Having One-Dimensional Stacking Disorder

Abstract While trying to react NbBr5 with sulfur in a closed tube, crystals of the new modification β-NbBr5 were obtained. Its X-ray diffraction patterns have sharp reflexions and diffuse streaks showing the presence of a one-dimensional disorder. From the sharp reflexions alone, a statistically averaged sub-structure results; it has the space group Ccmm and the lattice constants a0 = 644, b0 = 1867 and c0 = 615 pm. Taking into account the diffuse streaks, the true structure was deduced; its lattice constants are a = 2a0, c = Co, b indefinite due to the disorder. β-NbBr5 is isostructural to tantalum pentaiodide. It consists of layers of (NbBr5)2 molecules that are stacked with displacement faults in the direction of b. The bromine atoms have a hexagonal close-packing arrangement.