Understanding packing and interactions inside solids is important knowledge for crystal engineering aiming to build new desired compounds with specific physical and chemical properties  [1], as well as for understanding properties such as luminescence [2]. Two important interactions in organic, organometallic or protein structures are highlighted: hydrogen bonding [3] and π interactions (π-anion, π-cation and π-π-stacking) [4]. Both types of interaction are characterised by specific distances and angles, which can be easily determined and visualized using graphic software such as Diamond[5] or Mercury[6] for 3D structures. However, in case of modulated structure (3+1)D, this visualisation and interpretation is not so straightforward. In this contribution, we describe new tools developed for Jana2006/Jana2020 software in order to find and visualize π-π-stacking in (3+1)D modulated structures. The improvement of the π-π stacking vizualisation allowed us to understand the difference between two new polymorphs, α and β-Mn(dmp)Cl₂, which we use as a case study.

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[4] Martinez, C.R., & al. Chem. Sci. 3, 2191–2201 (2012). 

[5] Brandenburg, K.: DIAMOND. Crystal Impact GbR, Bonn, Germany (1999).

[6] Macrae, C.F., & al. J. Appl. Crystallogr. 41, 466–470 (2008).