Concerted Spin Crossover and Symmetry Breaking Yield Three Thermally and One Light‐Induced Crystallographic Phases of a Molecular Material

Four crystal phases are accessible by thermally and light-induced spin crossover associated with symmetry breaking for [FeIIH2L2MeH2L2Me](PF6)2 (H2L2Me is an acyclic hexadentate N6 Schiff base). In this novel molecular material, the arrays of FeII complex cations (high-spin: red triangles; low-spin: blue triangles) are separated by layers of counteranions (green zigzag lines).