Pressure-induced single-crystal-to-single-crystal nitrite ligand isomerisation accompanied by a piezochromic effect.

High-pressure structural study of a piezochromic crystal of a rare di- exo -nitrito nickel(II) complex supported by computational analysis is presented. The examined system is not photoswitchable, however, in the 0-6.2 GPa pressure range the crystal undergoes two phase-transitions accompanied by a colour change and the nitrite ligand isomerisation, which is unique.