Chapter 4 - Jacobs University

Chapter 9
Unpublished Results
9.2.3.1 X-ray crystallography
A block crystal of 17a with dimensions 0.16 x 0.14 x 0.05 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 K α radiation (λ = 0.71073 Å). Of the 149004 reflections
collected (2θ max = 57.64°, 99.2% complete), 10856 were unique (R int = 0.1383) and 13046
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, Si, K and Na atoms) and isotropic thermal
parameters converged at R = 0.0484 (I > 2σ(I)) and and R w = 0.1350 (all data). In the final
difference map the deepest hole was -3.1 e - Å-3 and the highest peak 4.6 e - Å-3.
The data for this crystal are summarized in Table 9.4.
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