X-Ray Structure of Aspirin

The X-ray structure of aspirin contains dimers formed by H-bonding between two benzoic acids functions. Note that there are four H-atoms shwon between the carboxy-oxygen atoms. Why might that be? Of course, the H-atoms go back and forth between two positions and the X-ray diffraction "sees" the average.


Figure. The X-ray structure of aspirin contains dimers formed by H-bonding between two benzoic acids functions.

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