Exchange Interactions and Magnetic Properties of a Molecular Mn -Ring Complex.

[Mn O(OAc) (HOAc)]  ⋅ x AcOH (x=6-9) represents a rare example of a compound containing molecular Mn -rings. These are formed by Mn (μ -O) subunits in which the high-spin Mn(III) centers are bridged by three pairs of acetate anions (AcO ). An AcOH molecule coordinates to one of the Mn atoms leading to [Mn (μ -O)(μ -OAc) (AcOH)]-units, designated in short as Mn -units, that are interconnected by acetate anions via the other two Mn atoms to form Mn -rings.

3D-Frameworks and 2D-networks of lanthanide coordination polymers with 3-pyridylpyrazole: photophysical and magnetic properties.

A series of 15 lanthanide-containing coordination polymers, both 3D- and 2D-networks, as well as complexes of Ln-trichlorides with 3-(3-pyridyl)pyrazole (3-PyPzH), were synthesized. A large structural diversity is observed depending on the ligand content: 3∞[Ln(3-PyPzH)Cl], Ln = Eu and Gd, of topology, 2∞[Sm(3-PyPzH)Cl], 2∞[Ln(3-PyPzH)Cl]·2solv, Ln = Eu, Tb, Dy, Ho and Er, solv = Tol and MeCN, of topology and 2∞[Ln(3-PyPzH)Cl], Ln = La and Nd, of topology with salt like complexes of the formula [(3-PyPzH)][Ln(3-PyPzH)Cl], Ln = Eu, Tb, Dy and Ho. The products were characterized by single-crystal and powder X-ray diffraction, high-temperature X-ray diffraction, differential thermal analysis and thermogravimetry (DTA/TG) combined with mass spectrometry, differential scanning calorimetry (DSC), IR-spectroscopy, UV-visible spectrophotometry, photoluminescence spectroscopy, and magnetic susceptibility.

Syntheses and Characterization of the Mixed-Valent Manganese(II/III) Fluorides MnF and MnF.

We obtained single crystals of the binary mixed-valent fluorides MnF and MnF using a high-pressure/high-temperature approach. MnF crystallizes isotypic to CaCrF in the monoclinic space group 2/ (No. 15), with = 8.

Coexistence of Two Different Distorted Octahedral [MnF ] Sites in K [MnF ]: Manifestation in Spectroscopy and Magnetism.

As a consequence of the static Jahn-Teller effect of the E ground state of Mn in cubic structures with octahedral parent geometries, their octahedral coordination spheres become distorted. In the case of six fluorido ligands, [MnF ] anions with two longer and four shorter Mn-F bonds making elongated octahedra are usually observed. Herein, we report the synthesis of the compound K [MnF ] through a high-temperature approach and its crystallization by a high-pressure/high-temperature route.

Model Dimeric Manganese(IV) Complexes Featuring Terminal Tris-hydroxotetraazaadamantane and Various Bridging Ligands.

A series of model dinuclear manganese(IV) complexes of the general formula [(HCOH)(L')Mn(μ-L)Mn(L')(HOCH)] is presented. These compounds feature capping 4,6,10-trihydroxo-3,5,7-trimethyl-1,4,6,10-tetraazaadamantane ligands derived from a polydentate oxime compound (L'). The bridging ligands L include azide (), methoxide (), and oxalate () anions.

C-H Bond Activation by an Imido Cobalt(III) and the Resulting Amido Cobalt(II) Complex.

The 3d-metal mediated nitrene transfer is under intense scrutiny due to its potential as an atom economic and ecologically benign way for the directed amination of (un)functionalised C-H bonds. Here we present the isolation and characterisation of a rare, trigonal imido cobalt(III) complex, which bears a rather long cobalt-imido bond. It can cleanly cleave strong C-H bonds with a bond dissociation energy of up to 92 kcal mol in an intermolecular fashion, unprecedented for imido cobalt complexes.

UF and the High-Pressure Polymorph HP-UF.

A laboratory-scale synthesis of UF is presented that utilizes the reduction of UF with sulfur in anhydrous hydrogen fluoride. An excess of sulfur can be removed by vacuum sublimation, yielding pure UF , as shown by powder X-ray diffraction, micro X-ray fluorescence analysis, infrared and Raman spectroscopy, as well as magnetic measurements. Furthermore, a single-crystalline, high-pressure modification of UF was obtained in a multi-anvil press at elevated temperatures.

A Revised Structure Model for the UCl Structure Type, Novel Modifications of UCl and UBr , and a Comment on the Modifications of Protactinium Pentabromides.

The redetermination of the crystal structure of trigonal UCl , which is the eponym for the UCl structure type, showed that certain atomic coordinates had been incorrectly reported. This led to noticeably different U-Cl distances within the octahedral UCl molecule (2.41 and 2.

Forcing substitution of tantalum by copper in 1T-TaS: synthesis, structure and electronic properties of 1T-Cu Ta S.

We investigated the compound 1T-Cu Ta S with respect to its synthesis, homogeneity range, structure and electronic properties. The average structure of 1T-Cu Ta S resembles that of the high-temperature phase of the layered transition metal dichalcogenide 1T-TaS in which tantalum is partially substituted by copper. 1T-Cu Ta S readily decomposes at elevated temperatures and can only be prepared and stabilized by a sufficiently high amount of sulfur excess.

The [U F ] Anion of Sr[U F ].

The D -symmetric dinuclear complex anion [U F ] of pastel green Sr[U F ] shows a hitherto unknown structural feature: The coordination polyhedra around the U atoms are edge-linked monocapped trigonal prisms, the U atoms are therefore seven-coordinated. This leads to a U-U distance of 3.8913(6) Å.

NOUF6 Revisited: A Comprehensive Study of a Hexafluoridouranate(V) Salt.

We have synthesized NOUF6 by direct reaction of NO with UF6 in anhydrous HF (aHF). Based on the unit cell volume and powder diffraction data, the compound was previously reported to be isotypic to O2 PtF6 , however, detailed structural data, such as the atom positions and all information that can be derived from those, were unavailable. We have therefore investigated the compound by using single-crystal and powder X-ray diffraction, IR, Raman, NMR, EPR, and photoluminescence spectroscopy, magnetic measurements, as well as chemical analysis, density determination, and quantum chemical calculations.

Spin Crossover and Valence Tautomerism in Neutral Homoleptic Iron Complexes of Bis(pyridylimino)isoindolines.

Homoleptic iron complexes of six bis(pyridylimino)isoindoline (bpi) ligands with different substituents (H, Me, Et, tBu, OMe, NMe2) at the 4-positions of the pyridine moieties have been prepared and studied with regard to temperature-dependent spin and redox states by a combination of (57)Fe Mössbauer spectroscopy, SQUID magnetometry, single-crystal X-ray diffraction analysis, X-band EPR, and (1)H NMR spectroscopy. While the H-, methyl-, and ethyl-substituted complexes remain in a pure high-spin state irrespective of the temperature, the 4-tert-butyl-substituted derivative shows spin-crossover behavior. The methoxy- and dimethylamino-substituted compounds were found to easily undergo oxidation.

Iron 10-thiacorroles: bioinspired iron(III) complexes with an intermediate spin (S=3/2) ground state.

A first systematic study upon the preparation and exploration of a series of iron 10-thiacorroles with simple halogenido (F, Cl, Br, I), pseudo-halogenido (N3 , I3 ) and solvent-derived axial ligands (DMSO, pyridine) is reported. The compounds were prepared from the free-base octaethyl-10-thiacorrole by iron insertion and subsequent ligand-exchange reactions. The small N4 cavity of the ring-contracted porphyrinoid results in an intermediate spin (i.

Self-organization of multifunctional surfaces--the fingerprints of light on a complex system.

Nanocomposite patterns and nanotemplates are generated by a single-step bottom-up concept that introduces laser-induced periodic surface structures (LIPSS) as a tool for site-specific reaction control in multicomponent systems. Periodic intensity fluctuations of this photothermal stimulus inflict spatial-selective reorganizations, dewetting scenarios and phase segregations, thus creating regular patterns of anisotropic physicochemical properties that feature attractive optical, electrical, magnetic, and catalytic properties.

Novel magnetic iron oxide nanoparticles coated with poly(ethylene imine)-g-poly(ethylene glycol) for potential biomedical application: synthesis, stability, cytotoxicity and MR imaging.

Magnetic iron oxide nanoparticles have found application as contrast agents for magnetic resonance imaging (MRI) and as switchable drug delivery vehicles. Their stabilization as colloidal carriers remains a challenge. The potential of poly(ethylene imine)-g-poly(ethylene glycol) (PEGPEI) as stabilizer for iron oxide (γ-Fe₂O₃) nanoparticles was studied in comparison to branched poly(ethylene imine) (PEI).

Ru9Zn7Sb8: a structure with a 2 × 2 × 2 supercell of the half-Heusler phase.

The title compound Ru(9)Zn(7)Sb(8) was synthesized via a high-temperature reaction from the elements in a stoichiometric ratio, and its structure was solved by a single-crystal X-ray diffraction method. The structure [cubic, space group Fm3m, Pearson symbol cF96, a = 11.9062(14) Å (293 K), and Z = 4] adopts a unique 2a(hh) × 2a(hh) × 2a(hh) supercell of a normal half-Heusler phase and shows abnormal features of atomic coordination against the Pauling rule.

Iron chelates of 2,2'-bidipyrrin: stable analogues of the labile iron bilins.

A unique series of halogenidoiron(III) complexes of the open-chain tetrapyrrolic ligand 2,2'-bidipyrrin (bpd) ([FeX(bdp)] X=F, Cl, Br, I) was prepared from simple pyrrolic and bipyrrolic precursors and iron chloride by a one-pot condensation/metalation strategy, followed by salt metathesis with CsF, LiBr, or NaI. Crystallographic analysis revealed that in all cases the 2,2'-bidipyrrin ligand is forced to reside in a helical conformation when bound to the iron atom. Whereas the extremely sensitive fluorido derivative was isolated as a CsF adduct and forms 1D polymeric chains in the solid state, the more stable chlorido, bromido, and iodido derivatives crystallize as discrete monomeric molecules with a distorted pentacoordinate iron(III) ion in an intermediate spin ground state.

The valence problem of Pd4Br4Te3.

Pd(4)Br(4)Te(3) was prepared from Pd, Te, and PdBr(2) at 700 K. Its structure was determined by single-crystal X-ray diffraction to be triclinic, P$\bar 1$, Pearson symbol aP22; a=842.5(2), b=845.

Trans-dichloro-tris([5]trovacenyl)stannate(iv), electro- and magneto-communication across a Cl-Sn-Cl backbone.

Reaction of [5]lithiotrovacene (TVC-Li) with tin dichloride affords the triradical complex (THF)(3)Li(+)[(TVC)(3)SnCl(2)](-) which was characterized by X-ray crystallography, cyclic voltammetry, EPR spectroscopy and magnetic susceptometry; redox splittings deltaE(1/2) ("electrocommunication") and the exchange parameters J(EPR) and J(chi) ("magnetocommunication") attest to inter vanadium interactions mediated by the central tin atom.

Cyanide-promoted demetalation of TrpyNiNCO: a route to sensitive metallotripyrrins of CoII, FeII, and MnII.

Etheral solutions of free base tripyrrins (HTrpy) were prepared by treatment of nickel isocyanate complexes (TrpyNiNCO) with excess cyanide. From these solutions sensitive metallotripyrrins with cobalt(II), iron(II), and manganese(II) ions (TrpyMX) and with a choice of external ligands X could be obtained in pure, crystalline form. Four cobalt and one iron chelate were characterized by X-ray crystallography.

Ferrimagnetic nanogranular Co3O4 through solvothermal decomposition of colloidally dispersed monolayers of alpha-cobalt hydroxide.

Co3O4 nanoparticles of 35 nm with a cauliflower-like morphology were obtained when a monolayer colloidal dispersion of dodecyl sulfate intercalated alpha-cobalt hydroxide in butanol was subjected to solvothermal hydrolytic decomposition. The nanogranular particles exhibit weakly ferromagnetic properties in contrast with both bulk and dispersed nanoparticulate Co3O4.