X-Ray Crystallography

2.0 Presentation of data in the manuscript

2.1 Title and summary

For an article reporting a crystallographic structure determination it is often appropriate, although not essential to indicate this information in the title, e.g.  by the words 'crystal structure of'. For full papers which contain several crystal structure determinations it is recommended that lengthy titles quoting the formula of all the structures determined be avoided. Whether or not the crystal structure determination is indicated in the title, reference should be made to it in the summary. The summary need not contain cell dimensions and other crystal data.

If the procedures for data collection and structure analysis were routine, their description should be particularly concise. When the analysis was not of a routine nature, the authors should briefly detail the procedures used.

2.2 Description

2.2.1 Full papers.  Where appropriate, the description may be given in textual or tabular form, although the latter is more appropriate if several structure determinations are being reported in one paper. A table of selected bond lengths and angles, with estimated standard deviations should be restricted to significant dimensions only (for example it is rarely necessary to include data for phenyl rings). Average values may be given (with a range of e.s.d.s) for chemically equivalent groups or for similar bonds. Differences from expected norms should be noted.

2.2.2 Communications. Details of the data collection and CCDC number should be given in a footnote or in the References/Notes section. Where given, selected bond lengths and angles, with estimated standard deviations, should be included in the figure caption and be restricted to significant dimensions only.

2.2.3 E-only journals.  Crystallographic data should be given in tabular form and details of the structure analysis should be given either as a footnote to the table or separately in the Experimental section. Tables of bond lengths and angles should be prepared as for full papers.

2.3 Illustrations

A conventional line drawing of the structure should normally be included except in the simplest cases and one perspective diagram (or stereo pair) if appropriate. Packing diagrams should not be included unless required to illustrate a specific chemical point. The atom numbering scheme should be clearly shown in one of the diagrams. Any differences from that required by standard rules of chemical nomenclature should be pointed out. Each atom of the asymmetric unit should be assigned an arabic numeral in parentheses following the chemical symbol: C(2), O(1''), etc.; it is often convenient to associate a particular number of primes with a particular asymmetric unit. Alternatively, roman numeral superscripts can be employed: C(2I) · · · C(2IV). For e-only journals, authors are encouraged to provide 3D interactive versions of their figures.

2.4 Data required for presentation in the manuscript

The following information need only be given in the manuscript if there is significant discussion of the crystallography: 

• Chemical formula and formula weight (M)
• Crystal system
• Unit-cell dimensions ( or pm, degrees) and volume, with estimated standard deviations, temperature
• Space group symbol (if non-standard setting give related standard setting)
• No. of formula units in unit cell (Z)
• Number of reflections measured and/or number of independent reflections, R_int
• Final R values (and whether quoted for all or observed data)
• Flack or Rogers parameter (if appropriate)                  

The following example demonstrates the application of the recommendations in the preceding sections in a full paper. For a communication, the headings should be omitted.