Guest water-induced structural transformation and spin-crossover variation of a two-dimensional Hofmann-type compound

In this paper, we report a two-dimensional (2D) Hofmann-type spin-crossover coordination polymer [FeII(o-NTrz)2PtII(CN)4]center dot H2O (o-NTrz = 4-(o-nitrobenzyl)imino-1,2,4-triazole). Due to the remarkable configurational flexibility of triazole-based ligand, the porous structure of this compound can be reversibly regulated by the loss of guest water molecules as a consequence of rotation of o-NTrz. The 180 degrees reorientation of the o-nitrobenzyl moiety not only induces a response of gate-closing/opening of the porous framework but also significantly modulates the spin transition temperature. The present investigation highlights the potential of Hofmann-type SCO compounds with flexible ligands in exploring unusual physical and chemical phenomena. A two-dimensional Hofmann-type coordination polymer [FeII(o-NTrz)2PtII(CN)4]center dot H2O (o-NTrz = 4-(o-nitrobenzyl)imino-1,2,4-triazole) shows changes in spin-crossover behavior due to the loss of water molecules and consequent rotation of ligand o-NTrz.