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Chapter 4 - Jacobs University

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<strong>Chapter</strong> 9<br />

Unpublished Results<br />

9.3.7.1 X-ray crystallography<br />

A colorless block of 26a with dimensions 0.23 x 0.08 x 0.02 mm 3 was mounted in a Hampton<br />

cryoloop for indexing and intensity data collection at 173 K on a Bruker D8 APEX II CCD<br />

single-crystal diffractometer using Mo Kα radiation (λ = 0.71073 Å). Of the 294738 reflections<br />

collected (2θ max = 55.26°, 99.2 % complete), 21912 were unique (R int = 0.1331) and 14901<br />

reflections were considered observed (I > 2σ(I)). Routine Lorentz and polarization corrections<br />

were applied and an absorption correction was performed using the SADABS program<br />

(Sheldrick, G. M.; Acta Crystallogr. 2007, A64, 112). Direct methods were used to locate the<br />

tungsten and hafnium atoms (SHELXS-97). Then the remaining atoms were found from<br />

successive Fourier maps (SHELXL-97). The final cycle of refinement, including the atomic<br />

coordinates, anisotropic thermal parameters (W, Hf, and K atoms) and isotropic thermal<br />

parameters converged at R = 0.0578 (I > 2σ(I)) and and R w = 0.1768(all data).<br />

The data for this crystal are summarized in Table 9.9.<br />

231

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