Papers by Andreas Oechsner
European Journal of Inorganic Chemistry, Jun 18, 2009
We report the synthesis of difluorenyl[2]borametallocenophanes of Zr and Hf. The ligand precursor... more We report the synthesis of difluorenyl[2]borametallocenophanes of Zr and Hf. The ligand precursor has been synthesized starting from 1,2-dibromo-1,2-bis(dimethylamino)diborane(4) upon reaction with Li[C 13 H 9 ]. All compounds have
European Journal of Inorganic Chemistry, 2009
We report the synthesis of difluorenyl[2]borametallocenophanes of Zr and Hf. The ligand precursor... more We report the synthesis of difluorenyl[2]borametallocenophanes of Zr and Hf. The ligand precursor has been synthesized starting from 1,2‐dibromo‐1,2‐bis(dimethylamino)diborane(4) upon reaction with Li[C13H9]. All compounds have been fully characterized by multinuclear NMR spectroscopy and, in addition, selected examples by X‐ray analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Winheim, Germany, 2009)
Chemistry – A European Journal, 2008
We report a series of [2]borametallocenophanes of Ti, Zr, and Hf with various ligand systems. The... more We report a series of [2]borametallocenophanes of Ti, Zr, and Hf with various ligand systems. The ligands have been synthesized in high yields starting from 1,2‐dibromo‐1,2‐bis(dimethylamino)diborane(4) upon reaction with Na[C5H5] and Li[C13H9], respectively. All compounds were fully characterized by multinuclear NMR spectroscopy and, for selected examples, by X‐ray analysis.
![Research paper thumbnail of Synthese, Struktur und Reaktivität von [2]Borametallocenophanen der Gruppe 4 Metalle : Ihr katalytisches Verhalten und die Eigenschaften der erhaltenen Polymere](https://a.academia-assets.com/images/blank-paper.jpg)
In der vorliegenden Arbeit wird die Darstellung einer Reihe monoarylsubstituierter Bisdimethylami... more In der vorliegenden Arbeit wird die Darstellung einer Reihe monoarylsubstituierter Bisdimethylamino-1-bromo-2-arlydiborane(4) beschrieben. Sowohl die Umsetzung der monoarylsubstituierten Ligandenvorstufen mit einem weiteren Äquivalent Lithium- oder Natriumaryl in einem Ether/Toluol-Gemisch als auch die Umsetzung von 1,2-Dibrom-bis(dimethylamino)diboran(4) mit einem mehrfachen Überschuss Lithium- oder Natriumaryl führte zur Bildung von diarylsubstituierten Diboranen(4). Umsetzung der Ligandenvorstufen mit Lithiumorganylen, wie beispielsweise Li[CH3] oder Li[C4H9] führt zu doppelt deprotonierten Verbindungen. Werden die dilithiierten Verbindungen mit Metallhalogeniden der Gruppe 4 in einem Toluol/Ether-Gemisch umgesetzt, können [2]Borametallocenophane erhalten werden. Von einigen der Verbindungen konnte die Struktur im Festkörper mittels Einkristallstrukturanalyse bestimmt werden. Die Verbindungen zeigen in Lösung ein dynamisches Gleichgewicht, welches durch die Flexibilität der B-B-B...
Chemistry - A European Journal, 2009
We present the synthesis and characterization of disila- and distanna ansa half-sandwich complexe... more We present the synthesis and characterization of disila- and distanna ansa half-sandwich complexes of Group 6 transition metals. These compounds exhibit high ring strain within the ansa bridge, which is the key factor for the insertion of elemental chalcogens.
Journal of Organometallic Chemistry, Nov 1, 2010
Here we report the synthesis and crystal structure of a new [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) ... more Here we report the synthesis and crystal structure of a new [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) 2 (SntBu 2 ) 2 ] with a sterically demanding distannanediyl bridge. The reactivity of the title compound towards selected main group elements was examined and in addition, this reactivity pattern was established for the related diboranediyl bridged [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) 2 (BNMe 2 ) 2 ].
Engineering Materials, 2009
Multifunctional Metallic Hollow Sphere Structures are an emerging new material category, belongin... more Multifunctional Metallic Hollow Sphere Structures are an emerging new material category, belonging like metal foams to the class cellular metals. Thanks to their advantageous mechanical and sound absorbing properties, Multifunctional Metallic Hollow Sphere Structures are very promising for various applications and our technological knowledge makes them ready for industrial usage. This reference gives a complete overview on this new materials class, the fundamentals, the applications and the perspective for future use. ...
Zeitschrift für anorganische und allgemeine Chemie, 2011
ABSTRACT Several „2”borametallocenophanes of group IV were used as catalysts for ethylene polymer... more ABSTRACT Several „2”borametallocenophanes of group IV were used as catalysts for ethylene polymerization reactions. The obtained polymers were characterized by GPC and DSC analyses. Furthermore, we investigated on the copolymerization of ethylene and 1-hexene catalyzed by „2”borazircocenophanes.
Materialwissenschaft und Werkstofftechnik, 2009
This work addresses the thermal finite element analysis (FE) of cellular aluminium with irregular... more This work addresses the thermal finite element analysis (FE) of cellular aluminium with irregular pore structures. The used finite element models are generated with computed tomography (CT) images as a basis. Three-dimensional brick elements of cubic shape are used. The material properties of each element are thereby defined based on corresponding pixels in computed tomography images. The proposed analysis with mapping of material properties on a regular finite element mesh is first validated on simple two dimensional models of regular geometries. The obtained results are compared to highly accurate reference solutions and analytical predictions. Subsequently, the FEM thermal analysis of closed cell Alporas J aluminium foam and open cell M-Pore J aluminium sponge is carried out determining the effective thermal conductivities of these materials in three perpendicular directions in order to investigate the anisotropic properties of both structures. The variability in the material volume (due to meso-inhomogeneities) has been inspected by computing different sub-volumes of the specimens. Fig. 8. Effective thermal conductivity of Alporas J aluminium foam. Abb. 8. Effektive thermische Leitfähigkeit von Alporas J Aluminiumschaum.
Materialwissenschaft und Werkstofftechnik, 2012
This special issue of Materials Science and Engineering Technology collects a selection of the sc... more This special issue of Materials Science and Engineering Technology collects a selection of the scientific papers presented in the EuroSPF 2010 conference organised by the Mondragon University in the city of San Sebastian, in the north of Spain.
Materials Letters, 2008
Numerical, analytical and experimental analyses are performed in order to determine the thermal c... more Numerical, analytical and experimental analyses are performed in order to determine the thermal conductivity of Metallic Hollow Sphere Structures (MHSS). Therefore, the geometry of this composite material is discretised and finite element analysis is performed. Furthermore, the thermal conductivity is estimated using Misnar's analytical model. Additionally, the Transient Plane Source method (TPS) is applied in order to perform thermal measurements on experimental samples. The findings of these approaches are compared and a good agreement is observed.
Journal of Organometallic Chemistry, 2010
Here we report the synthesis and crystal structure of a new [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) ... more Here we report the synthesis and crystal structure of a new [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) 2 (SntBu 2 ) 2 ] with a sterically demanding distannanediyl bridge. The reactivity of the title compound towards selected main group elements was examined and in addition, this reactivity pattern was established for the related diboranediyl bridged [2]ferrocenophane [Fe(h 5 -C 5 H 4 ) 2 (BNMe 2 ) 2 ].
Journal of Composite Materials, 2009
Abstract Porous composite materials constitute an innovative group of lightweight materials which... more Abstract Porous composite materials constitute an innovative group of lightweight materials which combine high specific stiffness, good damping properties, and thermal insulation with the ability to absorb large amounts of energy at a low constant stress level. In the scope of this study, adhesively bonded metallic hollow sphere structures (MHSS) fully embedded within the adhesive matrix are considered with aim to determine their macroscopic behavior under uniaxial impact loading conditions by means of parametric computational ...
International Journal of Adhesion and Adhesives, 2007
Simple analytical formulae have been reported in literature to extract basic elastic material pro... more Simple analytical formulae have been reported in literature to extract basic elastic material properties of adhesives subjected to tensile loading. The assumptions and simplifications of classical evaluation procedures may result in a remarkable error depending on the investigated material combination. This work proposes a new evaluation procedure for the butt-joint test of adhesive technology. The main idea is to determine the deformed shape of the adhesive layer and to relate the deformation, i.e. contraction and elongation, to a unique set of Young's modulus and Poisson's ratio. A numerical parameter study for different combinations of adherend/adhesive materials and butt-joint geometries has been performed to investigate the influence of these parameters on the adhesive deformation. Comprehensive diagrams are derived which relate the deformation of the adhesive layer to the complete set of linear elastic constants. r
Computational Materials Science, 2013
Composite Structures, 2007
A thin soft elasto-plastic interphase between two different media is under consideration. The int... more A thin soft elasto-plastic interphase between two different media is under consideration. The intermediate layer is assumed to be of infinitesimal thickness and is modelled by non-linear transmission conditions which incorporate the elasto-plastic material behaviour of the layer. FEM analysis of a bimaterial structure with such an imperfect elasto-plastic interface shows the efficiency of the approach and illustrates some restrictions of its application.
Chemistry - A European Journal, 2011
An important parameter for catalytic activity in the Ziegler-Natta process is the tilt angle betw... more An important parameter for catalytic activity in the Ziegler-Natta process is the tilt angle between the two coordi-nated aromatic rings. A large tilt angle results in better access to the metal centre and can be achieved by incorporation of a short and rigid ansa bridge. Because of the small size of the boron atom and its three-fold coordination, an aminoboranediyl bridge can enhance the stereoselectivity of the resulting polymers. Furthermore, the Lewis acidic boron atom lowers the electron density at the central metal, which also improves the catalytic activity and performance.
Chemistry - A European Journal, 2009
We present the synthesis and characterization of disila- and distanna ansa half-sandwich complexe... more We present the synthesis and characterization of disila- and distanna ansa half-sandwich complexes of Group 6 transition metals. These compounds exhibit high ring strain within the ansa bridge, which is the key factor for the insertion of elemental chalcogens.
Beilstein Journal of Organic Chemistry, 2009
An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central ... more An enantioselective route to four tricyclic amino acids and N-tosylamides, composed of a central norbornane framework with a 2-endo,3-endo-annelated pyrrolidine ring and a 5-endo-C 1 or -C 2 side chain, has been developed. A key intermediate was the chiral, N-Boc-protected ketone (1R,2S,6S,7R)-4-azatricyclo[5.2.1.0 2,6 ]decan-8-one, available from inexpensive endo-carbic anhydride in five steps and 47% yield. The rigid scaffold makes these amino acid derivatives promising candidates for β-turn-inducing building blocks in peptidomimetics and for chiral auxiliaries in asymmetric organocatalysis.
Angewandte Chemie, 2010
Professor S. S. Krishnamurthy zum 70. Geburtstag gewidmet Tertiäre Phosphane sind eindeutig die w... more Professor S. S. Krishnamurthy zum 70. Geburtstag gewidmet Tertiäre Phosphane sind eindeutig die wichtigsten Donorliganden bei den katalytisch aktiven d-Block-Organometallverbindungen. Die meisten der verwendeten PR 3 -Phosphane können sogar in Verbindungen mit mehreren Metallatomen als terminale Zwei-Elektronen-Donoren zu einem einzelnen Metallatom betrachtet werden. Die m-Verbrückung, der häufigste Koordinationstyp für R 2 P À -Phosphanide, wurde dagegen erst kürzlich für Phosphane gefunden. [3] Die ursprünglich isolierten Vier-Elektronen-Donorkomplexe enthalten ein Phosphoratom, das eine Pd-Pd-Bindung verbrückt, und übertragen zusätzliche Ladung an ein Metallatom entweder über eine P-H- (A in Schema 1) oder eine P-C-Bindung (B in Schema 1). ¾hnlich zum wohlbekannten m 3verbrückenden Zwei-Elektronen-Donor CO ist das tertiäre Phosphan PF 3 symmetrisch über einem Pd-Dreieck angeordnet (B in Schema 1). Zwei Phosphol-Liganden verbrücken eine Pd-Pd-Bindung in einem dikationischen Komplex ähnlich zu C in Schema 1. [7] PMe 3 wurde ursprünglich als asymmetrische Brücke (D in Schema 1) in einem zweikernigen Rhodium-Komplex gefunden. [8] Hier präsentieren wir die experimentelle und theoretische Elektronendichte von [Me 2 Al(m-Py) 2 P] (1; Py= 2-pyridyl) und die Struktur des m-verbrückenden HPPy 2 -Phosphans, das an zwei freie Pentacarbonylwolfram-Einheiten in dem zweikernigen Komplex [{(OC) 5 W} 2 PPy 2 (H)] (2) koordiniert ist. Die Ergebnisse beweisen, dass sowohl Py 2 P À als auch HPPy 2 sich wie Vier-Elektronen-Donoren verhalten.
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Papers by Andreas Oechsner