Abstract
A bidentate 2-methylimidazol-4-yl-methylideneaminobenzyl ligand (HL Me-Benz) reacts with FeIICl2·4H 2O and NaPF6 at a 3:1:1 molar ratio to yield a tris(2-methylimidazol-4-yl-methylideneaminobenzyl)iron(II) chloride hexafluorophosphate solvate with the formula of [FeII(HL Me-Benz)3]Cl·PF6·solvent. Meridional and facial geometrical isomers, i.e., mer-[FeII (HL Me-Benz)3]Cl·PF6·1.5H 2O (1·PF6·1.5H2O) and fac-[FeII(HLMe-Benz)3]Cl·PF 6·EtOH·H2O (2·PF6· EtOH·H2O), were selectively crystallized from methanol and ethanol solutions, respectively. fac-[FeII(HLMe-Benz) 3]Cl·SbF6·H2O (2·SbF 6·H2O) and fac-[FeII(HL Me-Benz)3]Cl·ClO4·EtOH· H2O (2·ClO4·EtOH·H2O) are synthesized in ethanol, using the corresponding anions. Each FeII ion has an octahedral coordination geometry with N6 donor atoms from three bidentate ligands. All three imidazole groups in both the fac- and mer-[FeII(HLMe-Benz)3]2+ cations are hydrogen-bonded to neighboring three Cl- ions, and each Cl - ion is hydrogen-bonded to three imidazole groups of three neighboring complex cations; this results in the formation of hydrogen-bonded assembly structures. mer-Complex 1·PF6·1.5H 2O forms a heterochiral two-dimensional (2D) network structure comprised of cyclic {mer-[FeII(HLMe-Benz) 3]2+⋯Cl-}3 units with an ΔΔΛ or ΛΛΔ configuration; the PF 6- ions occupy the spaces between the 2D layers. All the fac-complexes have isomorphous cubane-like tetrameric structures, i.e., {fac-[FeII(HLMe-Benz)3]2+⋯ Cl-}4. The tetranuclear structure comprises four homo-chiral fac-Δ- or fac-Λ-[FeII(HLMe-Benz) 3]2+ cations and four Cl- ions interconnected by twelve imidazole-chloride hydrogen bonds to form a chiral cubane supramolecule that encapsulates one counter anion. In the crystal lattice, the cubane-like tetramers with opposite chiralities are alternately arrayed. The temperature dependence of the magnetic susceptibilities and Mössbauer spectra reveal that the fac-complexes show incomplete spin crossover behavior, while the mer-complex shows a gradual spin crossover between high-spin (HS, S = 2) and low-spin (LS, S = 0) states.
Original language | English |
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Pages (from-to) | 1489-1498 |
Number of pages | 10 |
Journal | Polyhedron |
Volume | 52 |
DOIs | |
Publication status | Published - Mar 22 2013 |
Keywords
- Bidentate ligand
- Geometrical isomer
- Hydrogen bond
- Iron(II) complex
- Optical isomer
- Spin crossover
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry