Chapter 4 - Jacobs University

Chapter 9
Unpublished Results
9.2.2.1 X-ray crystallography
A yellow crystal of 16a with dimensions 0.27 x 0.23 x 0.08 mm 3 was mounted in a Hampton
cryoloop for indexing and intensity data collection at 173 K on a Bruker D8 APEX II CCD
single-crystal diffractometer using Mo Kα radiation (λ = 0.71073 Å). Of the 255904 reflections
collected (2θ max = 59.98°, 99.3% complete), 10856 were unique (R int = 0.1402) and 16664
reflections were considered observed (I > 2σ(I)). 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). Direct methods were used to locate the
tungsten and yttrium atoms (SHELXS-97). Then the remaining atoms were found from
successive Fourier maps (SHELXL-97). The final cycle of refinement, including the atomic
coordinates, anisotropic thermal parameters (W, Y, Sb, and Na atoms) and isotropic thermal
parameters (O and Na atoms) converged at R = 0.0762 (I > 2σ(I)) and and R w = 0.1999 (all data).
In the final difference map the deepest hole was -1.9 e - Å-3 and the highest peak 3.4 e - Å-3.
The data for this crystal are summarized in Table 9.3.
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