Chapter 4 - Jacobs University

Chapter 3 The Wheel-Shaped Cu 20
3.3 X-ray crystallography
A blue block with dimensions 0.09 x 0.07 x 0.06 mm 3 was mounted on a glass fiber for indexing
and intensity data collection at 153 K on a Bruker D8 SMART APEX CCD single-crystal
diffractometer using Mo K α radiation (λ=0.71073 Å). Of the 9102 unique reflections
(2q max =56.128), 5826 reflections (R int =0.083) were considered observed (I>2s(I)). Direct
methods were used to solve the structure and to locate the tungsten and copper atoms (SHELXS-
97). Then the remaining atoms were found from successive difference maps (SHELXL-97). The
final cycle of refinement, including the atomic coordinates, anisotropic thermal parameters (W,
Cu, P, K and Cl atoms), and isotropic thermal parameters (O atoms) converged at R=0.068 and
R w =0.179 (I>2s(I)). No lithium ions could be located crystallographically. In the final difference
map the deepest hole was -3.054 e Å -3 and the highest peak 4.663 e Å -3 . Routine Lorentz and
polarization corrections were applied and an absorption correction was performed using the
SADABS program (Sheldrick, G. M.; Acta Crystallogr. 2007, A64, 112). The data for this crystal
are summarized in Table 3.1.
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