Organisationsprozesse des mentalen Lexikons und ihre elektronische Modulation beim Fremdsprachenerwerb

Der Beitrag setzt zur Klärung spezifischer Probleme des L2-Wortschatzerwerbs bei der Organisation des "mentalen Lexikons" an. Das Sprachverarbeitungsmodell von Levelt dient dabei als Bezugspunkt, um gängige Modelle zu Aufbau und Organisation des bilingualen mentalen Lexikons zu diskutieren. Im Mittelpunkt steht die angemessene Berücksichtigung sprachspezifischer Unterschiede in der Konstitution semantisch-konzeptueller Netze. Vor diesem Hintergrund werden Möglichkeiten der elektronischen Modulation semantischer Netze vorgestellt, die für den Fremdsprachenerwerb genutzt werden können

trans-Diaqua­bis[5-carb­oxy-4-carboxyl­ato-2-(4-pyridinio)-1H-imidazol-1-ido-κ2 N 3,O 4]iron(II)

In the title complex, [Fe(C10H6N3O4)2(H2O)2], the FeII atom is located on a twofold rotation axis and is coordinated by two trans-positioned N,O-bidentate and zwitterionic 5-carboxy-2-(pyridinium-4-yl)-1H-imidazol-1-ide-4-carboxylate H2PIDC− ligands and two water mol­ecules in a distorted environment. In the crystal packing, a three-dimensional network is constructed via hydrogen-bonding involving the water mol­ecules, uncoordinated imidazole N atom, protonated pyridine N and carboxyl­ate O atoms

[(Z)-1-({3-[(3-Amino­prop­yl)(2-nitro­benz­yl)amino]­prop­yl}imino­meth­yl)naphthalen-2-olato]copper(II) perchlorate

In the title compound, [Cu(C24H27N4O3)]ClO4, the CuII atom has a distorted square-planar coordination geometry and is surrounded by an N3O donor set composed of a secondary amine N, a primary amine H, an imino N and a naphthalen-2-olate O atom. An intra­molecular N—H⋯O hydrogen bond occurs. In the crystal, mol­ecules are held together by inter­molecular N—H⋯O hydrogen bonds, leading to the formation of a three-dimensional network

Against the Norm: Non Irving–Williams Transmetalation in Transition Metal Dimers

We report the synthesis and characterization of three dinuclear 3d3d′ complexes, CuCu ([CuII2L(NO3)2] CuII2L(NO3)2]), MnMn ([MnII2L(MeOH)2(NO3)2][MnII2L(MeOH)2(NO3)2]), and CuMn ([CuIIMnIIL(NO3)2]), that utilize the ligand, H2L (6,6′-dimethoxy-2,2’-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol). The relative stabilities of these complexes were investigated using experimental and computational techniques, revealing a non-Irving-Williams transmetalation, whereby a MnII ion can displace a CuII ion from its binding pocket in CuCu to yield the more stable CuMn complex. Magnetic characterization of the reported complexes revealed an unexpected ferromagnetic coupling between the two CuII ions of CuCu with J = +63.0 cm–1

From Gas Phase Observations to Solid State Reality: The Identification and Isolation of Trinuclear Salicylaldoximato Copper Complexes

Conditions have been identified in which phenolic aldoximes and ketoximes of the types used in commercial solvent extraction processes can be doubly deprotonated and generate polynuclear Cu complexes with lower extractant:Cu molar ratios than those found in commercial operations. Electrospray mass spectrometry has provided an insight into the solution speciation in extraction experiments and has identified conditions to allow isolation and characterization of polynuclear Cu-complexes. Elevation of pH is effective in enhancing the formation of trinuclear complexes containing planar {Cu3-μ3-O}4+ or {Cu3-μ3-OH}5+ units. DFT calculations suggest that such trinuclear complexes are more stable than other polynuclear species. Solid structures of complexes formed by a salicylaldoxime with a piperidino substituent ortho to the phenolic OH group (L9H2) contain two trinuclear units in a supramolecular assembly, {[Cu3OH(L9H)3(ClO4)](ClO4)} 2, formed by H-bonding between the central {Cu3-μ3-OH}5+ units and oxygen atoms in the ligands of an adjacent complex. Whilst the lower ligand:Cu molar ratios provide more efficient Cu-loading in solvent extraction processes, the requirement to raise the pH of the aqueous phase to achieve this will make it impractical in most commercial operations because extraction will be accompanied by the precipitation (as oxyhydroxides) of Fe(III) which is present in significant quantities in feed solutions generated by acid leaching of most Cu ores

Synthesis of a boronic acid anhydride based ligand and its application in beryllium coordination

The synthesis of a boronic acid anhydride‐based ligand containing one three‐ and one four‐coordinated boron atom is presented. This ligand was successfully employed as a tridentate κ¹N,κ²O‐ligand in the coordination of beryllium chloride and both the ligand and the resulting complex have been structurally characterized. While the boron‐element separations are within the typical range of related homo‐nuclear compounds, the corresponding beryllium‐element distances are rather long, suggesting unexpectedly high electron density at the beryllium center. Incorporation of a beryllium atom in a six‐membered ring causes no more distortion than the corresponding boron atom, suggesting that analogous ligand systems could be used in boron and beryllium coordination chemistry. The generated hetero‐tri‐nuclear complex enables the direct comparison of bond lengths and angles at beryllium and boron atoms in similar coordination environments and can act as a monomolecular model for beryllium borates

The chemistry and metallurgy of beryllium

Beryllium (Be), the first of the group 2 alkali-earth ele­ments, is a silver-gray metal possessing an unmatched combination of physical and mechanical properties, which are vital for a variety of applications that offer tre­mendous benefits to society. It is the lightest workable metal, only two-thirds the weight of aluminium, yet it has six times the stiffness of steel, making it an ideal mate­rial for stiffness-dependent and weight-limited applica­tions. The chart in Fig. 1 illustrates how much beryllium outclasses other engineering materials with respect to thermal conductivity and dimensional stability (ability of a material to retain its uniformity under stress measured as the Young's modulus to density ratio). These unique properties of beryllium translate into performance en­hancement in the end product, for instance the James Webb Space Telescope (JWST: see Fig. 2). The next gen­eration James Webb Space Telescope, scheduled to be launched in 2018 as NASA's replacement for the Hubble telescope, will utilise a 6.5 meter wide beryllium mirror to reveal images of distant galaxies 200 times beyond what has ever been sighted

Synthesis and Characterization of Symmetrically versus Unsymmetrically Proton-Bridged Hexa-Iron Clusters

Syntheses and magnetic and structural characterization of hexa-iron complexes of derivatized salicylaldoximes are discussed. Complexation of Fe(BF4)2·6H2O with each ligand (H2 L1 and H4 L2) in a methanolic-pyridine solution resulted in hexa-iron compounds (C1 and C2, respectively), which each contain two near-parallel metal triangles of [Fe3-μ3-O], linked by six fluoride bridges and stabilized by a hydrogen-bonded proton between the μ3-O groups. Within each metal triangle of C2, Fe(III) ions are connected via the amine "straps" of (H4 L2-2H). Variable-temperature magnetic susceptibility and Mössbauer data of C1 and C2 indicate the presence of dominant antiferromagnetic interactions between the high-spin (S = 5/2) Fe(III) centers. For C1, two quadrupole doublets are observed at room temperature and 5 K, consistent with structural data from which discrete but disordered [Fe3-μ3-O] and [Fe3-μ3-OH] species were inferred. For C2, a single sharp quadrupole doublet with splitting intermediate between those determined for C1 was observed, consistent with the symmetric [Fe3-μ3-O···H···μ3-O-Fe3] species inferred crystallographically from the very short μ3-O···μ3-O separation. The differences in the physical properties of the complexes, as seen in the Mössbauer, X-ray, and magnetic data, are attributed to the conformational flexibility imparted by the nature of the linkages between the closely related ligands