Dear Adnan Qadir ,

remember that a CIF file is not generally obtained from a standard compound. Usually, they are experimental data related to real samples, therefore several impurities, minor elements may interfere upon the final fitting result.

You may get the compound formulae from a crystallographic file, however, tiny quantities may not have interfered with crystallographic properties, so they will not be present at the file.

Natural samples would present several minor elements, inclusions, impurities that are sometimes ignored in the main phase description, by consequence not described in the Crystallographic file, by the absence of the elemental information.

The safe situation is to have extra information such as XRF, elemental composition describing your particular sample.

Best regards

WNM

Thank you very much, Wagner.

I would like to add that we prepare coordination compounds in the lab and we have already known the suggested formula. During my work, I usually get single crystals for a compound, then we make elemental analysis, always I get CHN results identical with the formula of crystallographic data. This means that the formulae from crystallographic file has high accuracy.

Dear Adnan Qadir thank you for this very interesting technical question. In my opinion single-crystals X-ray diffraction data cannot replace classical elemental analysis. Here is the main reason: The X-ray data will give you the exact chemical composition of the compound, but only for the crystal which has been measured. Quite often the bulk material contains only very few well-formed crystals, from which one of them is selected for the X-ray dffraction study. Thus the composition of this single crystal does not tell you anything about the chemical composition of the bulk material. In some cases only a by-product of the reaction crystallizes nicely, while the main product only forms a microcrystalline powder. In other cases the good crystals contain a different amount of solvent of crystallization. Thus when it comes to publication of your work, please keep in mind that the X-ray diffraction data are not a suitable replacement for elemental analysis.

Many thanks Prof. Edelmann.