The X-ray crystal structure determination of tetraphenylarsonium tris(η5-cyclopentadienyl)di-isothiocyanatouranate(IV)

Abstract

The crystal structure of the title compound has been determined from three-dimensional X-ray diffraction data. The compound crystallises in space group P, with a= 15.570(7), b= 13.727(5), c= 9.082(4)Å, α= 94.8(1), β= 104.9(1), γ= 99.6(1)°, and Z= 2. The structure was solved by Patterson and Fourier methods; full-matrix least-squares refinement based on 3 584 reflections gave a final R value of 0.053. The co-ordination about the uranium atom in the anion [U(cp)₃(NCS)₂]^–(cp = cyclopentadienyl) is a trigonal bipyramid with three π-bonded cp rings in the equatorial plane (U–ring centre distances 2.48, 2.49, and 2.50 Å) and two nitrogen-bonded thiocyanate groups in the axial positions (U–N 2.46 and 2.50 Å). The As–C distances in the cation [AsPh₄]⁺ range from 1.873 to 1.886 Å and the C–As–C angles fall in the range 106.5–111.9°. The structure is discussed in conjunction with information available for [U(cp)₃(NCS)(NCCH₃)] and [U(cp)₃(NCCH₃)₂]₂[UO₂Cl₄]·2L(L = buta-1,3-diene).