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Figure 2
Contact enrichment ratios in crystals of ketones as a function of SH, the hydrogen proportion on the Hirshfeld surface. In all the graphs, for a more compact representation, the scale for E values larger than unity has been modified. For a better graphical representation, E values > 1 are replaced by E′ = 2 − 1/E, in order to obtain E′ values in the interval [0., 2.]. In this way, two inverse enrichment ratios are located at the same distance on each side of the line E = 1. The E′ and E scale are both represented in this first graph. Points corresponding to small denominators Rxy < 2% are shown in a smaller size, as they correspond to ratios of small actual and random surfaces. The purple dotted line represents EOHmax, the mathematically highest possible enrichment [E^{\prime}_{\rm OH}] value if the whole oxygen atom surface is involved in O⋯H contacts. The maximum contact surface is ROHmax = SO, therefore the upper limit is EOHmax = SO/(SO × SH) = 1/ SH. The black dotted line represents the lowest possible EHH value occurring when all C and O atoms interact with H: EHHmin = (2 × SH − 1)/SH2. The linear fits on contact enrichments versus surface content are performed for all figures in EXCEL using the E′ values.

IUCrJ
Volume 4| Part 2| March 2017| Pages 158-174
ISSN: 2052-2525
https://doi.org/10.1107/S2052252516020200