Chapter 4 - Jacobs University

Chapter 9
Unpublished Results
9.2.1.1 X-ray crystallography
A colorless needle of 15a with dimensions 0.38 x 0.10 x 0.03 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 278364 reflections
collected (2θmax = 46.5°, 99.6% complete), 7672 were unique (Rint = 0.1853) and 19584
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, As, Na and Cs atoms) and isotropic thermal
parameters converged at R = 0.1057 (I > 2σ(I)) and and Rw = 0.2782 (all data). In the final
difference map the deepest hole was -3.1e - Å -3 and the highest peak 4.0 e - Å -3 . The data for this
crystal are summarized in Table 9.2.
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