Heteropentanuclear {Ru(II)Cu(II)} Kuratowski Complexes Assembled from a Ruthenium(II) Precursor Complex to Study Competing Exchange Interactions in M(II)(ta) Networks [ta(-) = 1,2,3-Triazolate].

We report a directed two-step synthesis toward pentanuclear Kuratowski complexes. First, six 5,6-dimethylbenzo[1,2,3]triazole ligands (MebtaH) are coordinated to a single Ru(II) ion, providing a topologically ideal template for the addition of further metal ions. The synthesis and crystal structures of [RuCuX(Mebta)] [X = acetylacetonate (acac) and tris(3,5-dimethyl-1-pyrazolyl)borate (Tp*)] are described.

Broadband magnetic resonance spectroscopy in MnSc[Formula: see text]S[Formula: see text].

Recent neutron scattering experiments suggested that frustrated magnetic interactions give rise to antiferromagnetic spiral and fractional skyrmion lattice phases in MnSc[Formula: see text]S[Formula: see text] . Here, to trace the signatures of these modulated phases, we studied the spin excitations of MnSc[Formula: see text]S[Formula: see text] by THz spectroscopy at 300 mK and in magnetic fields up to 12 T and by broadband microwave spectroscopy at various temperatures up to 50 GHz. We found a single magnetic resonance with frequency linearly increasing in field.

Density Functional Theory Approach to the Vibrational Properties and Magnetic Specific Heat of the Covalent Chain Antiferromagnet KFeS.

Ternary potassium-iron sulfide, KFeS, belongs to the family of highly anisotropic quasi-one-dimensional antiferromagnets with unusual "anti-Curie-Weiss" susceptibility, quasi-linearly growing with a rising temperature up to 700 K, an almost vanishing magnetic contribution to the specific heat, drastically reduced magnetic moment, etc. While some of the measurements can be satisfactorily described, the deficiency of the entropy changes upon the magnetic transition and the spin state of the iron ion remains a challenge for the further understanding of magnetism. In this work, high-quality single-crystalline samples of KFeS were grown by the Bridgman method, and their stoichiometry, crystal structure, and absence of alien magnetic phases were checked, utilizing wave-length dispersive X-ray electron-probe microanalysis, powder X-ray diffraction, and Fe Mössbauer spectroscopy, respectively.

How Correlations and Spin-Orbit Coupling Work within Extended Orbitals of Transition-Metal Tetrahedra of 4d/5d Lacunar Spinels.

Spin-orbit quartet ground states are associated with rich phenomenology, ranging from multipolar phases in f rare-earth borides to magnetism emerging through covalency and vibronic couplings in d transition-metal compounds. The latter effect has been studied since the 1960s on t octahedral units in both molecular complexes and extended solid-state lattices. Here we analyze the = 3/2 quartet ground state of larger cubane-like entities in lacunar spinels, composed of transition-metal () tetrahedra caged by chalcogenide ligands ().

Doping Control of Magnetic Anisotropy for Stable Antiskyrmion Formation in Schreibersite (Fe,Ni) P with S symmetry.

Magnetic skyrmions, vortex-like topological spin textures, have attracted much interest in a wide range of research fields from fundamental physics to spintronics applications. Recently, growing attention is also paid to antiskyrmions emerging with opposite topological charge in non-centrosymmetric magnets with D or S symmetry. In these magnets, complex interplay among anisotropic Dzyaloshinskii-Moriya interaction, uniaxial magnetic anisotropy, and magnetic dipolar interactions generates various magnetic textures.

Cooperative Large-Hysteresis Spin-Crossover Transition in the Iron(II) Triazolate [Fe(ta)] Metal-Organic Framework.

The metal-organic framework [Fe(ta)] (Hta = 1-1,2,3-triazole) containing Fe(II) ions and 1,2,3-triazolate ligands shows a reversible phase transition while retaining the cubic crystal symmetry and space group 3 (no. 227). The phase transition between room temperature (RT-[Fe(ta)]; = 16.

Evidence for Electronically Driven Ferroelectricity in a Strongly Correlated Dimerized BEDT-TTF Molecular Conductor.

By applying measurements of the dielectric constants and relative length changes to the dimerized molecular conductor κ-(BEDT-TTF)_{2}Hg(SCN)_{2}Cl, we provide evidence for order-disorder type electronic ferroelectricity that is driven by the charge order within the (BEDT-TTF)_{2} dimers and stabilized by a coupling to the anions. According to our density functional theory calculations, this material is characterized by a moderate strength of dimerization. This system thus bridges the gap between strongly dimerized materials, often approximated as dimer-Mott systems at 1/2 filling, and nondimerized or weakly dimerized systems at 1/4 filling, exhibiting a charge order.

Single-Crystal to Single-Crystal Transformation of a Nonporous Fe(II) Metal-Organic Framework into a Porous Metal-Organic Framework via a Solid-State Reaction.

We report the synthesis of an air-stable nonporous coordination compound based on iron(II) centers, formate anions, and a 4,4'-bipyrazole (HBPZ) ligand. Upon thermal treatment, a porous metal-organic framework (MOF) formed due to decomposition of the incorporated formate anions. This decomposition step and the following structural changes constituted a single-crystal to single-crystal transformation.

Ultra-robust high-field magnetization plateau and supersolidity in bond-frustrated MnCrS.

Frustrated magnets provide a promising avenue for realizing exotic quantum states of matter, such as spin liquids and spin ice or complex spin molecules. Under an external magnetic field, frustrated magnets can exhibit fractional magnetization plateaus related to definite spin patterns stabilized by field-induced lattice distortions. Magnetization and ultrasound experiments in MnCrS up to 60 T reveal two fascinating features: (i) an extremely robust magnetization plateau with an unusual spin structure and (ii) two intermediate phases, indicating possible realizations of supersolid phases.

Thickness dependence of the triplet spin-valve effect in superconductor-ferromagnet-ferromagnet heterostructures.

Background: In nanoscale layered S/F1/N/F2/AF heterostructures, the generation of a long-range, odd-in-frequency spin-projection one triplet component of superconductivity, arising at non-collinear alignment of the magnetizations of F1 and F2, exhausts the singlet state. This yields the possibility of a global minimum of the superconducting transition temperature T c, i.e.

[Co5Tp*4(Me2bta)6]: A Highly Symmetrical Pentanuclear Kuratowski Complex Featuring Tris(pyrazolyl)borate and Benzotriazolate Ligands.

The pentanuclear Co(II) complex [Co5Tp*4(Me2bta)6] containing N-donor ligands (5,6-dimethyl benzotriazolate; Me2bta6) and N-donor capping ligands (tris(3,5-dimethyl-1-pyrazolyl)borate; Tp*) was prepared by a simple and efficient ligand exchange reaction from [Co5Cl4(Me2bta)6] and tetra-n-butyl ammonium tris(3,5-dimethyl-1-pyrazolyl)borate. Compared to the precursor complex [Co5Cl4(Me2bta)6], which contains one Co(II) ion in octahedral and four Co(II) ions in tetrahedral coordination geometry, the title compound features all five Co(II) ions in an octahedral coordination environment while keeping a high complex symmetry. This results in modified properties including improved solubility and distinct magnetic behavior as compared to the precursor complex.

A U(V) chalcogenide: synthesis, structure, and characterization of K2Cu3US5.

The compound K2Cu3US5 was obtained by the reaction of K2S, UCl4, CuCl, and S at 973 K. K2Cu3US5 crystallizes in a new structure type in space group Cmcm of the orthorhombic system in a cell of dimensions a = 3.9374(6) A, b = 13.

An organometallic chimie douce approach to new Re(x)W(1-x)O3 phases.

Re(x)W(1-x)O3.H2O and Re(x)W(1-x)O3 phases are prepared by a new organometallic chimie douce concept employing the organometallic precursor methyltrioxorhenium.

Formation of Zn(1-x)MnxS nanowires within mesoporous silica of different pore sizes.

Arrays of highly ordered Zn(1-x)MnxS quantum wires with x ranging from 0.01 to 0.3 and with lateral dimensions of 3, 6, and 9 nm were synthesized within mesoporous SiO2 host structures of the MCM-41 and SBA-15 type.

Melanin in the extracellular matrix of germlings of Botrytis cinerea.

Previous work on the composition of the extracellular matrix of germlings of the plant pathogenic fungus Botrytis cinerea demonstrated the presence of carbohydrate, protein, and simple lipids; which, together, comprised 50-60% of the dry weight. Here we show that most of the remaining mass of the extracellular matrix consists of a chemically inert dark pigment with the electron paramagnetic resonance characteristics of a melanin. Scanning electron micrographs of the purified pigment, and transmission electron micrographs of thin sections made using the pigment indicate that it has a filamentous structure.