Square and Butterfly Tetranuclear [Co2Ln2] Clusters Built from the Same Building Blocks but Displaying Different Magnetic Properties: Structural Variation by Means of Solvent and the Radii of Ln3+Ions

Heterobimetallic 3d-4f complexes supported by a Schiff-base tripodal ligand

Complexes featuring multiple metal centres are of growing interest regarding metal-metal cooperation and its tuneability. Here the synthesis and characterisation of heterobimetallic complexes of a 3d metal (4: Mn, 5: Co) and lanthanum supported by a (1,1,1-tris[(3-methoxysalicylideneamino)methyl]ethane) ligand is reported, as well as discussion of their electronic structure via electron paramagnetic resonance (EPR) spectroscopy, electrochemical experiments and computational studies. Competitive binding experiments of the ligand and various metal salts unequivocally demonstrate that in these heterobimetallic complexes the 3d metal (Mn, Co) selectively occupies the κ6-N3O3 binding site of the ligand, whilst La occupies the κ6-O6 metal binding site in line with their relative oxophilicities. EPR spectroscopy supported by density functional theory analysis indicates that the 3d metal is high spin in both cases (S = 5/2 (Mn), 3/2 (Co)). Cyclic voltammetry studies on the Mn/La and Co/La bimetallic complexes revealed a quasi-reversible Mn2+/3+ redox process and poorly-defined irreversible oxidation events respectively.

The solvent-induced isomerization of silver thiolate clusters with symmetry transformation

The solvent-induced isomerizations of Ag12 clusters with symmetry transformations were realized by changing the coordinated solvent molecules at room temperature.

Syntheses, Structures, and Magnetic Properties of a Series of Heterotri-, Tetra- and Pentanuclear LnIII⁻CoII Compounds

Three types of Ln(III)⁻Co(II) heterometallic compounds, LnCo₂(L1)₇(bipy)₂ (Ln = Pr-1, Eu-2, Sm-3, Gd-4, Tb-5, Dy-6) (L1 = 4-chlorobenzoate, bipy = 2,2'-bipyridine), Ln₂Co₂(L₂)10(bipy)₂ (Ln = Sm-7, Gd-8, Tb-9, Dy-10, Ho-11, Er-12, Yb-13), (L2 = 2,4-dichlorobenzoate, bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline), and Ln₂Co₃(L1)12(bipy)₂ (Ln = Ho-14, Er-15, Yb-16), were synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR spectroscopy and magnetic measurements. Structural analyses revealed that 14⁻16 take on a unique linear pentanuclear structural motif. Interestingly, the Ho-containing compound 14 exhibits magnetic relaxation behavior.

Regulation of magnetic relaxation behavior by replacing 3d transition metal ions in [M2Dy2] complexes containing two different organic chelating ligands

Two [MIII2DyIII2] complexes (M = Fe for 1 and Co for 2) with mixed organic ligands were obtained. Complex 2 exhibits single molecule magnet behavior with U_eff = 64.0(9) K.

Four 3d–4f heterometallic Ln45M7 clusters protected by mixed ligands

A series of high-nuclearity 3d–4f clusters Ln₄₅M₇ were obtained based on acetate and propionate as mixed protecting ligands and ClO₄⁻ and CO₃²⁻ as mixed anion templates.

A Series of Lanthanide-Germanate Oxo Clusters Decorated by 1,10-Phenanthroline Chromophores

A series of lanthanide-germanate oxo clusters, [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2H₂O [Ln = Dy (1a) and Er (1b); T = -CH₂CH₂COO^- group; phen = 1,10-phenanthroline], [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆]·2phen·16H₂O [Ln = Sm (2a), Eu (2b), and Gd (2c)], and [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]·2phen·13H₂O (3), have been hydrothermally synthesized from the reactions of bis(carboxyethylgermanium sesquioxide) and Ln₂O₃ with auxiliary phen chromophores. Compounds 1a and 1b consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆] and free H₂O molecules, where cage clusters are arranged in a CsCl type, while compounds 2a-2c consist of cage clusters [Ln₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₆], free phen, and free H₂O molecules, where cage clusters are arranged in a NaCl type. Compound 3 consists of the one-dimensional neutral chain [Ho₈(phen)₂Ge₁₂(μ₃-O)₂₄T₁₂(H₂O)₁₄]_n and free H₂O molecules. These compounds provide the first examples of p-f heterometallic [Ge-O-Ln] oxo clusters decorated by phen chromophores. The photoluminescent and magnetic properties of all compounds have been investigated.

Bis-phenoxido and bis-acetato bridged heteronuclear {Co(III)Dy(III)} single molecule magnets with two slow relaxation branches

Two bis-μ-phenoxido-bis-μ-acetato heterobimetallic {Co(III)Dy(III)} complexes and , formulated as [Co(III)Dy(III)L(μ-OAc)2(NO3)2] derived from the comparable hexadentate Schiff bases N,N'-ethylenebis(3-ethoxysalicylaldimine) and N,N'-ethylenebis(3-methoxysalicylaldimine) were synthesized and X-ray structure analysis confirms their nearly identical structures. These are the first examples of bis(μ-phenoxido)-bis(μ-carboxylato) {Co(III)Dy(III)} systems. The AC susceptibility measurements show that both complexes exhibit a field-induced slow magnetic relaxation with two relaxation branches. While the high-frequency process spans the usual range of the relaxation time for analogous single molecule magnets (τ0 ∼ 10(-7) s), the low-frequency branch is as slow as τ ∼ 0.1 s at T = 1.9 K and B = 0.2 T.

Linking cobalt–water chains with cis-1,4-cyclohexanedicarboxylate bridges to form a 2D network exhibiting spin-canted antiferromagnetism

A 2D magnetic network consisting of water-bridged 1D Co²⁺ chains and cis-CHDA bridges displays spin-canted antiferromagnetism with spin-glass behavior.

Crystal structure of the inverse crown ether tetra-kis-[μ2-bis-(tri-methyl-sil-yl)amido]-μ4-oxido-dicobalt(II)disodium, [Co2Na2{μ2-N(SiMe3)2}4](μ4-O)

The title compound, [Co2Na2{μ2-N(SiMe3)2}4](μ4-O), (I), represents a new entry in the class of inverse crown ethers. In the mol-ecule, each Co atom is formally in the oxidation state +II. The structure contains one half of a unique mol-ecule per asymmetric unit with the central μ4-oxido ligand residing on an inversion center, leading to a planar coordination to the Na and Co atoms. In the crystal, bulky tri-methyl-silyl substituents prevent additional inter-actions with cobalt. However, weak inter-molecular Na⋯H3C-Si inter-actions form an infinite chain along [010]. The structure is isotypic with its Mg, Mn and Zn analogues.