A photomagnetic study of orthorhombic and tetragonal low spin polymorphs of compound [Fe(L)2](BF4)2 revealed different properties and thermal stability of their metastable high spin states. Furthermore, the reversible thermally induced phase/spin transition between low spin and high spin orthorhombic phases was studied by variable temperature UV/VIS spectroscopy.

Utilization of 2-hydroxybenzophenone derivatives for the preparation of iron(iii) Schiff base complexes resulted in a series of high-spin, mostly antiferromagnetically coupled systems.

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A series of novel iron(III) complexes of the general formula [Fe(L)X] (where L is a dianion of pentadentate Schiff base ligand N,N'-bis({2-hydroxy-3,5-dimethylphenyl}phenyl)methylidene-1,6-diamino-3-azapentane=H L1 for 1 and 2; N,N'-bis({2-hydroxy-3-ethoxyphenyl}methylidene)-1,6-diamino-3-azapentane=H L2 for 3 and 3⋅C H O) and X is terminal pseudohalido ligand (X=N for 1, X=NCS for 2, and X=NCSe for 3 and 3⋅C H O) were synthesized and thoroughly characterized. Magnetic measurements revealed the above room temperature spin crossover for isomorphic complexes 1 and 2 (T =441 K and T =435 K, respectively), whereas the solvent-free complex 3 showed a half complete spin crossover (T =250 K), which was detected by variable temperature crystallography as well. On the other hand, solvated complex 3⋅C H O exhibited permanent high spin state behaviour and either recrystallization or in situ thermal desolvation converts 3⋅C H O to solvent-free and spin-crossover-active form 3. Magnetic properties of all the reported complexes were also supported by EPR spectroscopy experiments and in addition, DFT and ab initio calculations were employed for the evaluation of the g-factor and zero field splitting parameters.