Fmoc-Leu-ψ[CH2NCS] undergoes a reversible isomorphous phase transition upon cooling. The crystal structure at 100 K displays a short N![[double bond, length as m-dash]](http://www.rsc.org/images/entities/char_e001.gif)
CS⋯NCS intermolecular interaction, which has been characterized based on experimental charge density analysis, as a stabilizing interaction with both σ-holes and π-holes acting cooperatively.
![Graphical abstract: Observation of a reversible isomorphous phase transition and an interplay of “σ-holes” and “π-holes” in Fmoc-Leu-ψ[CH2-NCS]](http://hg.y866.cn/compound/lib/scimg/usr/1/C4CC08751H.jpg)
