Where are the lone pairs? QC and QCT

The article by Guzmán-Hernández & Jancik [(2024). Acta Cryst. C80, 766–774] is an excellent example of how QC–QCT (quantum crystallography–quantum chemical topology) methodology can extract structural information from a crystal.

Monoprotonated species of 2-amino­malonyl difluoride, [C₃H₄F₂NO₂][H₂F₃]

The monoprotonated species of 2-amino­malonyl difluoride, [C₃H₄F₂NO₂][H₂F₃], is particularly inter­esting for the protonation in superacidic media, as well as in Lewis acidic media, due to its two acyl fluoride moieties. The crystal structure is the first single-crystal X-ray diffraction measurement of this com­pound or its salts.