Chiroptical and magnetic properties of star-shaped Fe complexes from chiral Schiff bases. Structural and magnetic correlations based on continuous shape measures

Chiral Co3Y Propeller-Shaped Chemosensory Platforms Based on 19F-NMR

Two propeller-shaped chiral Co^III₃Y^III complexes built from fluorinated ligands are synthesized and characterized by single-crystal X-ray diffraction (SXRD), IR, UV-vis, circular dichroism (CD), elemental analysis, thermogravimetric analysis (TGA), electron spray ionization mass spectroscopy (ESI-MS), and NMR (¹H, ¹³C, and ¹⁹F). This work explores the sensing and discrimination abilities of these complexes, thus providing an innovative sensing method using a ¹⁹F NMR chemosensory system and opening new directions in 3d/4f chemistry. Control experiments and theoretical studies shed light on the sensing mechanism, while the scope and limitations of this method are discussed and presented.

Slow magnetic relaxation for cobalt(II) complexes in axial bipyramidal environment: an S = 1/2 spin case

A new family of magnetically mononuclear cobalt(II) complexes with formula [{Ni^II(L)Co^II(H₂O)₂(MeOH)}{Ni^II(L)}₂](ClO₄)₂ where H₂L1 = bis(N,N'-bis(3-methoxysalicylidene)ethylene-1,2-diamine) (1), H₂L2 = bis(N,N'-bis(3-methoxysalicylidene)propane-1,2-diamine) (2) and [{Cu^II(L4)}₂Co^II](ClO₄)₂ (3) where H₂L4 = bis(N,N'-bis(3-ethoxysalicylidene)cyclohexane-1,2-diamine) have been obtained employing non chiral or enantiomerically pure Schiff bases. The structural studies have been carried out by single crystal X-ray and powder diffraction. Dynamic magnetic studies indicate that some members of this family present field induced slow relaxation of the magnetization and its response has been compared with the magnetically diluted [Zn_0.9Co_0.1] complex 1D. Ultra-low frequency Raman spectroscopy has been used to relate the slow relaxation with lattice vibrations.

Self-assembly of a trigonal bipyramidal architecture with stabilisation of iron in three spin states

Self-assembly and characterisation of a supramolecular trigonal bipyramidal iron cage containing an [Fe^III(μ₂-F)₆(Fe^II)₃]³⁺ star motif at its core is reported. The complex can be formed in a one step reaction using an heterotopic ligand that supports site-specific incorporation of iron in three distinct electronic configurations: low-spin Fe^II, high-spin Fe^II and high-spin Fe^III, with iron(II) tetrafluoroborate as the source of the bridging fluorides. Formation of a μ₂-F bridged mixed-valence Fe^II-Fe^III star is unprecedented. The peripheral high-spin Fe^II centres of the mixed-valence tetranuclear star incorporated in the iron cage are highly anisotropic and engage in F-mediated antiferromagnetic exchange with the central Fe^III ion.

Chiral Versus Non-Chiral [MnIII 6 MnII NaI ], [MnIII 6 MnII 2 NaI 2 ] and [MnIII 3 MnII NaI ] Clusters Derived from Schiff Bases or the Fight for Symmetry

The reaction in basic media of manganese chloride with Schiff bases derived from the condensation of o-vanillin with different chiral/racemic aminoalcohols yielded in a family of complexes in which the nuclearity, symmetry and magnetic behavior is controlled by changing the position of the chiral carbon. Chiral and racemic clusters with [Mn^III ₆ Mn^II Na^I ], [Mn^III ₆ Mn^II ₂ Na^I ₂ ] and [Mn^III ₃ Mn^II Na^I ] metallic core have been structurally and magnetically characterized. The racemic clusters with an odd number of chiral ligands exhibit the anomalous mixing of ligands with different conformation. Related racemic compounds have been reviewed.

Synthesis, structure and magnetism of a new ionic pentanuclear iron cluster

A new ionic pentanuclear FeIII cluster, namely, triethylazanium tetrakis(μ2-5-amino-1,2,3,4-tetrazolido)tetrakis(μ3-4-chloro-2-{[(1H-tetrazol-1-id-5-yl)imino]methyl}phenolato)di-μ3-oxido-pentairon(III) acetonitrile monosolvate monohydrate, (C6H16N)[Fe5(C8H4ClN5O)4(CH2N5)4O2]·CH3CN·H2O, was synthesized using microvial synthesis methods and characterized by elemental analysis, FT–IR spectroscopy, single-crystal X-ray diffraction and thermogravimetric analysis. Magnetic studies reveal that the complex displays dominant antiferromagnetic intracluster interactions between the FeIII ions through the μ3-oxide bridges.

Syntheses, crystal structures and magnetic properties of a series of luminescent lanthanide complexes containing neutral tetradentate phenanthroline-amide ligands

Six lanthanide compounds have been prepared from a neutral tetra-dentate ligand. Their luminescent and magnetic properties were investigated in detail.

Decanuclear FeIII clusters with hemiacetal ligands: a new {M10(μ3-O)8} cluster core

The characterization of a Fe^III₁₀ cluster with α-methyl-2-pyridinemethanolate lead us to explore the direct syntheses of medium nuclearity Fe^III clusters with aldehydes in methanol. The complexes exhibit an unprecedented {Fe₁₀(μ₃-O)₈} cluster core.