Evaluate the outliers in the Sb-Cl bond length distribution.

•	In order to inspect just those CSD structures that contain unusually short Sb-Cl bond lengths: first deselect all hits in the histogram by clicking on the Deselect button, then highlight the two histogram bins located around 1.85Å using the horizontal bar located directly under the histogram:

 

•	Click on the View structures tab to see the CSD entries that contribute to the selected bins. You will notice that all of the selected observations come from a single crystal structure: (CSD refcode: NARLEY).

•	Use the Information, Diagram and 3D_Visualiser buttons on the left of the View structures tab to examine the structure. Can you account for the unusually short Sb-Cl bonds?

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After an initial inspection the structure looks reasonable, further investigation is clearly needed. To view the original publication reporting the crystal structure, click on the Information button, then click on the Digital Object Identifier (DOI) hyperlink in the Literature Reference field. Note that a subscription to the publication in question will normally be required to view the on-line article.

•	The structure in question is referred to as 8b in the publication. Does the information given in the Results and Discussion section provide any clues to the reason for the unusually short Sb-Cl bond lengths?

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The structure is reported as containing a SbF6- counter-ion, not SbCl6-. It is possible that the structure was incorrectly deposited with the database as the hexachloro-antimony ion, where, in fact, it should be a hexafluoro-antimony ion. Are the reported bond lengths of around 1.85Å more consistent with that expected for a Sb-F bond? Check this by running a Mogul search on SbF6. Should this structure (CSD refcode: NARLEY) be included in our Sb-Cl bond length analysis?