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.

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Professor S. S. Krishnamurthy zum 70. Geburtstag gewidmet Tertiäre Phosphane sind eindeutig die wichtigsten Donorliganden bei den katalytisch aktiven d-Block-Organometallverbindungen.[1] 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-Verbrü-ckung, der häufigste Koordinationstyp [2] 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- [4] (A in Schema 1) oder eine P-CBindung (B in Schema 1).[5] ¾hnlich zum wohlbekannten m 3 -verbrückenden Zwei-Elektronen-Donor CO ist das tertiäre Phosphan PF 3 symmetrisch über einem Pd-Dreieck angeordnet [6] (B in Schema 1). Zwei Phosphol-Liganden verbrü-cken 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. [12] Bemerkenswerterweise ist das Phosphanid sogar nach zweifacher P = N-Bindungsspaltung mit Organo-

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.

A conventional recovery method has an adverse effect towards unconventional reservoir production. A nanoparticle leads as a primary candidate to develop the unconventional reservoir and it is considered as one of the latest technology in oil and gas industry. Therefore this research is intended to study the effects of Carbon Nanotubes (CNT) towards interfacial tension. Practically MWCNTs were successfully synthesized using CVD technique by pyrolizing toluene and ferrocene in inert gas environment and characterized using X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) in order to understand its structure, shape, size and morphology. The characterization results show the CNTs are in cylindrical shape and well aligned. After characterization, a pendant drop experiment was carried out to further understand the effect of Carbon Nanotubes on Interfacial Tension (IFT). Since the Carbon Nanotubes are very "cloudy" the drop phase could not be identified and the Interfacial Tension was not calculated by the software. Due to this major setback, the Surface Tension was calculated with different concentration.

Several zigzag and armchair single-walled carbon nanotubes (CNTs) were modeled by a commercial finite element package and their vibrational behavior was studied. Numerous computational tests with different boundary conditions and different bending angles were performed. Both computational and analytical results were compared. It was shown that the computational results are in good agreement with the analytical calculations in the case of straight tubes. In addition, it was concluded that the natural frequency of straight armchair and zigzag CNTs increases by increasing the chiral number of both armchair and zigzag CNTs. It was also revealed that the natural frequency of CNTs with higher chirality decreases by introducing bending angles. Nevertheless, the influence of increasing bending angle on the natural frequency of armchair and zigzag CNTs with lower chiral number is almost negligible.