A family of homochiral spin-crossover iron(II) imidazole Schiff-base complexes

• Four homochiral spin-crossover iron(II) imidazole Schiff-base complexes have been successfully synthesized.
• 1–4 displayed obviously spin-crossover behavior at 257, 375, 137 and 282 K, respectively.
• The different SCO behaviors may result from substitution effect, packing mode, and intermolecular interactions.

Four novel homochiral mononuclear spin-crossover iron(II) complexes 1–4 have been successfully synthesized by subcomponent self-assembly of Fe(ClO4)2, 1-substituted imidazole-2-carboxaldehyde and optical phenylethylamine derivatives. X-ray crystallography revealed that the iron(II) center in 1–4 assumed an octahedral coordination environment with 6 N donor atoms from three unsymmetrical bidentate chiral Schiff-base ligands. [Fe(Ln)3]2 + components were chiral with either Λ or Δ configuration due to the screw coordination arrangement of the chiral ligands around Fe(II) center. Circular dichromism spectra confirmed the presence of non-racemic chiral metal centers in solution for 1–4. Magnetic measurements revealed that 1–4 displayed obviously spin-crossover behavior at 257, 375, 137 and 282 K, respectively. The different SCO behaviors of 1–4 may result from substitution effect, packing mode, and intermolecular interactions.

Four novel homochiral mononuclear spin-crossover iron(II) complexes 1–4 have been successfully synthesized by subcomponent self-assembly. [Fe(Ln)3]2 + components in 1–4 were chiral with either Λ or Δ configuration due to the screw coordination arrangement of the chiral ligands around Fe(II) center. 1–4 displayed obviously spin-crossover behavior at 257, 375, 137 and 282 K, respectively.Figure optionsDownload as PowerPoint slide