Peculiar Spin-Crossover Behavior in the 2D Polymer K[Fe(5Cl-thsa)].

A potassium salt of the NSO-coordination Fe(III) anion K[Fe(5Cl-thsa)] () (5Cl-thsa - 5-chlorosalicylaldehyde thiosemicarbazone) is synthesized and characterized structurally and magnetically over a wide temperature range. Two polymorphs of salt characterized by the common 2D polymer nature and assigned to the same orthorhombic space group have been identified. The molecular structure of the minor polymorph of was solved and refined at 100, 250, and 300 K is shown to correspond to the LS configuration.