Lanthanide hydroxide cubane clusters anchoring ferrocenes: model compounds for fixation of organometallic fragments on a lanthanide oxide surface

Postsynthetic Installation of Lanthanide Cubane Clusters in a 3D Hydrogen-Bonded Framework of IrIII4ZnII4 Multicarboxylates

Immersing single crystals of (Δ)4-K6[Ir4Zn4O(l-cysteinate)12]·nH2O (K6[1Ir]·nH2O) bearing 12 free carboxylate groups, which was newly prepared from Δ-H3[Ir(l-cysteinate)3], ZnBr2, ZnO, and KOH, in an aqueous solution of lanthanide(III) acetate produced Ln2[1Ir]·nH2O (2Ln; Ln = LaIII, CeIII, PrIII, and NdIII) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1Ir]·nH2O (3Ln; Ln = SmIII, EuIII, GdIII, TbIII, DyIII, ErIII, HoIII, TmIII, YbIII, and LuIII) in a single-crystal-to-single-crystal transformation manner. X-ray crystallography showed that the KI ions in K6[1Ir]·nH2O are completely exchanged by the LnIII ions in 2Ln and 3Ln, retaining the 3D hydrogen-bonded framework that consists of the IrIII4ZnII4 complex anions of [1Ir]6-. While 2Ln contained the LnIII ions as isolated aqua species, the LnIII ions in 3Ln existed as cationic cubane clusters of [Ln4(OH)4(OAc)3(H2O)7]5+; these were linked by [1Ir]6- anions through carboxylate groups in a 3D polymeric structure. 3Ln showed magnetic and photoluminescence properties that are characteristically observed for discrete LnIII species in the solid state.

Oxidation of europium with ammonium perfluorocarboxylates in liquid ammonia: pathways to europium(II) carboxylates and hexanuclear europium(III) fluoridocarboxylate complexes

The novel coordination polymer [Eu(O₂CCF₃)₂(dmf)₂]_∞ (1) (dmf = N,N-dimethylformamide) containing europium(II) and the two new compounds (NH₄)₂[Eu₆F₈(O₂CCF₃)₁₂(CF₃COOH)₆] (2) and (NH₄)₂[Eu₆F₈(O₂CC₂F₅)₁₂(C₂F₅COOH)₆]·8C₂F₅COOH (3), both based on hexanuclear europiate(III) complexes, were synthesized from precursors with a Eu²⁺ : Eu³⁺ ratio >1, obtained by reaction of europium metal with ammonium perfluorocarboxylates in liquid ammonia. In the crystal structure of 1 the europium(II) ions are bridged by carboxylate groups and N,N-dimethylformamide to form polymeric chains with Eu²⁺⋯Eu²⁺ distances of 408.39(13)-410.49(13) pm. The compound crystallizes in the triclinic space group P1̄ (Z = 2). To the best of our knowledge, this is the first example of a (solvated) perfluorocarboxylate containing a lanthanoid in a subvalent oxidation state. In the crystal structures of 2 and 3 the europium(III) ions are bridged by fluoride ions and carboxylate groups to form hexanuclear complex anions with an octahedral arrangement of the cations. The Eu³⁺⋯Eu³⁺ distances are in the range of 398.27(15)-400.93(15) pm in 2 and 395.37(4)-399.78(5) pm in 3, respectively. Both compounds crystallize in the monoclinic space group type P2₁/n (Z = 4) and are the first examples of octahedro-hexanuclear europium carboxylates for which fluoride is reported as a bridging ligand. In all compounds the oxidation state of europium was monitored via¹⁵¹Eu Mössbauer and photoluminescene spectroscopy.

Single-Crystal-to-Single-Crystal Installation of Ln4 (OH)4 Cubanes in an Anionic Metallosupramolecular Framework

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single-crystal-to-single-crystal (SCSC) transformation is presented. Soaking single crystals of K₆ [Rh₄ Zn₄ O(l-cys)₁₂ ] (K₆ [1]; l-H₂ cys=l-cysteine) in a water/ethanol solution containing Ln(OAc)₃ (Ln³⁺ =lanthanide ion) results in the exchange of K⁺ by Ln³⁺ with retention of the single crystallinity, producing Ln₂ [1] (2_Ln ) and Ln_0.33 [Ln₄ (OH)₄ (OAc)₃ (H₂ O)₇ ][1] (3_Ln ) for early and late lanthanides, respectively. While the Ln³⁺ ions in 2_Ln exist as disordered aqua species, those in 3_Ln form ordered hydroxide-bridged cubane clusters that connect [1]^6- anions in a 3D metal-organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts.

Ferrocene-Supported Compartmental Ligands for the Assembly of 3d/4f Complexes

Site-specific coordination ligands, also known as compartmental ligands, have been used for the preparation of heterometallic complexes. These ligands, by virtue of possessing specific binding sites, can encapsulate different metal ions in their coordination pockets. Such compartmental ligands have been widely used for the preparation of heterometallic 3d/4f complexes which have applications in molecular magnetism. This Review summarizes our efforts in the use of ferrocene-based compartmental ligands for the preparation of heterometallic 3d/4f complexes, some of which are single-molecule or single-ion magnets.

Effect of coordination geometry on the magnetic properties of a series of Ln2 and Ln4 hydroxo clusters

Tetra and di-nuclear Lanthanide hydroxo clusters have been synthesized and characterized magnetically.

Tetrametallic Thorium Compounds with Th4E4 (E = S, Se) Cubane Cores

Tetrametallic thorium compounds with a Th₄E₄ core (E = S, Se) having a distorted cubane structure can be prepared by ligand-based reductions of elemental E with thorium chalcogenolates, prepared by in situ oxidation of Th metal with a 3:1 mixture of PhEEPh and F₅C₆EEC₆F₅. Four compounds, (py)₈Th₄S₄(μ₂-SPh)₄(SC₆F₅)₄, (py)₈Th₄S₄(μ₂-SPh)₄(SeC₆F₅)₄, (py)₈Th₄Se₄(μ₂-SePh)₄(SeC₆F₅)₄, and (py)₈Th₄Se₄(μ₂-SePh)₄(SC₆F₅)₄, were isolated and characterized by NMR spectroscopy and X-ray diffraction. These compounds clearly demonstrate the chemical impact of ring fluorination, with the less-nucleophilic EC₆F₅ ligands occupying the terminal binding sites and the EPh ligands bridging two metal centers. For this series of compounds, crystal packing and intermolecular π···π and H-bonding interactions result in a consistent motif and crystallization in a body-centered tetragonal unit cell. Solution-state ⁷⁷Se NMR spectroscopy reveals that the solid-state structures are maintained in pyridine.

Synthesis, structure, and physical properties of new rare earth ferrocenoylacetonates

New ferrocenoylacetonate complexes of several rare earth elements, [Ln(fca)3(bpy)]·MeC6H5 (Ln = Pr (), Eu (), Gd (), Tb (), Dy (), Ho (), Y (); bpy - 2,2'-bipyridine; Hfca - FcCOCH2COMe) as well as scandium ferrocenoylacetonate [Sc(fca)3]·0.5MeC6H5 (), were synthesized and characterized by single crystal X-ray diffraction analysis. In the crystal lattice of the isostructural complexes , two [Ln(fca)3(bpy)] molecules form a pair due to stacking interactions between the bpy ligands. The Ln(3+) ions are coordinated in a square antiprism geometry with a coordination number of 8. The Sc(3+) ions in complex are coordinated in an octahedral geometry. Thermolysis of complexes was studied under air and argon atmospheres; in the first case, it affords perovskites LnFeO3 as one of the products. Complexes display single-molecule magnet properties, and the effective relaxation barrier for the Dy complex , was found to be Δeff/kB = 241 K, which is one of the highest values obtained for a mononuclear β-diketonate lanthanide complex.

Mixed-anion templated cage-like lanthanide clusters: Gd27 and Dy27

Two record-large odd-numbered Ln₂₇ lanthanide clusters, each one featuring one CO₃²⁻ and eight ClO₄⁻ groups as mixed anion templates, were obtained by controlling the hydrolysis of the Ln³⁺ ions in the presence of simple propionate ligands.

New NIR-emissive tetranuclear Er(iii) complexes with 4-hydroxo-2,1,3-benzothiadiazolate and dibenzoylmethanide ligands: synthesis and characterization

Two new Er complexes were prepared and studied.

Novel lanthanide-based polymeric chains and corresponding ultrafast dynamics in solution

Two types of structurally related one-dimensional coordination polymers were prepared by reacting lanthanide trichloride hydrates [LnCl(3)·(H(2)O)(m)] with dibenzoylmethane (Ph(2)acacH) and a base. Using cesium carbonate (Cs(2)CO(3)) and praseodymium, neodymium, samarium, or dysprosium salts yielded [Cs{Ln(Ph(2)acac)(4)}](n) (Ln = Pr (1), Nd (2), Sm (3), Dy (4)) in considerable yields. Reaction of potassium tert-butoxide (KOtBu) and the neodymium salt [NdCl(3)·(H(2)O)(6)] with Ph(2)acacH resulted in [K{Nd(Ph(2)acac)(4)}](n) (5). All polymers exhibit a heterobimetallic backbone composed of alternating lanthanide and alkali metal atoms which are bridged by the Ph(2)acac ligands in a linear fashion. ESI-MS investigations on DMF solutions of 1-5 revealed a dissociation of all the five compounds upon dissolution, irrespective of the individual lanthanide and alkali metal present. Temporal profiles of changes in optical density were acquired performing pump/probe experiments with DMF solutions of 1-5 via femtosecond laser spectroscopy, highlighting a lanthanide-specific relaxation dynamic. The corresponding relaxation times ranging from seven picoseconds to a few hundred picoseconds are strongly dependent on the central lanthanide atom, indicating an intramolecular energy transfer from ligands to lanthanides. This interpretation also demands efficient intersystem crossing within one to two picoseconds from the S(1) to T(1) level of the ligands. Magnetic studies show that [Cs{Dy(Ph(2)acac)(4)}](n) (4) has slow relaxation of the magnetization arising from the single Dy(3+) ions and can be described as a single-ion single molecule magnet (SMM). Below 0.5 K, hysteresis loops of the magnetization are observed, which show weak single chain magnet (SCM) behavior.

Synthesis and structural characterization of cationic 5-hydroxy-1,3-diketonate stabilized dinuclear complexes and tetranuclear lanthanoid clusters

5-Hydroxy-1,3-diketonate ligands have been found to stabilize dimeric complexes and tetrameric lanthanoid clusters dependent on the degree of steric bulk provided by the presence or absence of a methoxy group. Treatment of (R/S,Z)-1'-hydroxy-3-(hydroxy(phenyl)methylene)bi(cyclopentan)-2-one (Hhpb) and the p-methoxyphenyl derivative (Hhmb) with [LnCl(2)(H(2)O)(6)]Cl yields clusters of composition [Ln(4)(Cl)(2)(O)(hpb)(6)]Cl(2) (Ln = Nd (1), Ho (2), Tb (3), and Er (4)) and [Ln(2)(hmb)(5)]Cl (Ln = La (5), Nd (6), Tb (7), Dy (8), and Er (9)). Single crystal X-ray analysis of the tetranuclear cluster has revealed the lanthanoid core to be in a tetrahedral arrangement around a central mu(4)-oxygen, bridged by symmetrical chlorides and shrouded in six bridging hpb ligands. The dimeric complexes are stabilized by three bridging and two terminal hmb ligands. In each instance, double or single cationic charges respectively are balanced by chloride anions.