Two-Step Spin-Crossover with Three Inequivalent FeII Sites in a Two-Dimensional Hofmann-Type Coordination Polymer.

An unprecedented two-step spin-crossover behavior with the sequence of γHS =1↔γHS =3/4↔γHS =1/4 was observed in two-dimensional Hofmann type coordination polymer [Fe(isoq)2 {Ag(CN)2 }2 ] (isoq=isoquinoline), which resulted from three crystallographically inequivalent FeII sites with distinct transition temperatures.