A reversible metal-ligand bond break associated to a spin-crossover.

The [Fe(II)L(CN)(2)].H(2)O complex, dicyano[2,13-dimethyl-6,9-dioxa-3,12,18-triazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene]iron(II) monohydrate, exhibits a thermal induced metal-ligand bond break reversible in the solid state and associated to a spin crossover that corresponds to an unprecedented structurally characterized modification of the coordination metal environment from a hepta-coordinate high spin state to a hexa-coordinate low spin state.