Abstract

The structural changes that occur in the strongly hysteretic spin-crossover complex [Fe(qsal-I)2]NTf2 (1) have been determined for the full width of the hysteresis. In the cooling mode, structural changes are abrupt, while those in the warming mode are more gradual, mirroring the magnetic profile of 1. The anion conformational change previously observed in the cooling mode is found to be reversible, with the largest changes occurring where the spin transition is most abrupt. Packing in the structure involves supramolecular 1D chains of [Fe(qsal-I)2]+ formed by orthogonal π-πinteractions. Pronounced scissoring of the 1D chains is observed, which may be tied to the anion conformational change and may be collectively responsible for the strong cooperativity found in 1.