A series of symmetric and asymmetric binuclear α-diimine nickel(II) complexes toward ethylene polymerization were successfully synthesized and characterized by 1HNMR. All the catalysts were typically activated with MAO and displayed good activity at room temperature under 1atm ethylene pressure. The symmetric catalyst containing isopropyl on l...

a variety of group 4 metal catalytic systems (c2-symmetric {ebthi}-, {sbi}-type zirconocene complexes (c2-1–4); c1-symmetric (c1-5–8) and cs-symmetric (cs-9) {cp/flu}-type zirconocene complexes; cp*2zrcl2 (cp* 2-10)), half-metallocene complexes (cpticl3, hm-11), constrained-geometry (cgc-12) titanium catalysts) and post-metallocene catalysts (dow’s ortho-metallated amido-pyridino hafnium comple...

A variety of group 4 metal catalytic systems (C2-symmetric {EBTHI}-, {SBI}-type zirconocene complexes (C2-1–4); C1-symmetric (C1-5–8) and Cs-symmetric (Cs-9) {Cp/Flu}-type zirconocene complexes; Cp*2ZrCl2 (Cp* 2-10)), half-metallocene complexes (CpTiCl3, HM-11), constrained-geometry (CGC-12) titanium catalysts) and post-metallocene catalysts (Dow’s ortho-metallated amido-pyridino hafnium comple...

This study describes the synthesis of five novel C2-symmetric organocatalysts that facilitate the on-water asymmetric aldol reaction at low catalyst loading (1 mol%) without the use of additives. Each catalyst is composed of two diprolinamide units joined by a symmetric alkyl bridging group allowing for systematic modulation of catalytic site proximity. Typically, catalysts in this manuscript w...

Novel C2-symmetric diiminosphosphoranes and diketimines are useful ligands for Pd-and Cu-catalyzed C±C bond forming reactions, Angermund's molecular modeling based on accessible molecular surface serving as a guide in predicting catalyst activity. The ®rst highly enantioselective diphosphites as ligands in Rh-catalyzed hydrogenation are also described, the selectivity principle being based on i...

The oxidation of ketones by monometallic [Pd(CH3CN)2(S)-Tol-BINAP](BF4)2 A or [Pd(CH3CN)2(S)-METBOX](BF4)2 B in aqueous THF containing copper(II) bromide produced chiral α-bromoketones. The α-bromoketone products were obtained with moderate to high enantiomeric excess (68-89% ee) and good isolated yields (70-90%). The highest optical purities were 89% ee for cycloheptanone. Catalyst B gave slig...

Carbon nanotubes have been explored as interconnects in solid acid fuel cells to improve the link between nanoscale Pt catalyst particles and macroscale current collectors. The nanotubes were grown by chemical vapor deposition on carbon paper substrates, using nickel nanoparticles as the catalyst, and were characterized using scanning electron microscopy and Raman spectroscopy. The composite el...

Albert J. van Reenen and Omar Sultan Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa Reprint requests to Dr. A. J. van Reenen. Fax: +27-21-8084967. E-mail: [email protected] Z. Naturforsch. 2007, 62b, 362 – 366; received November 1, 2006 Dedicated to Prof. Helgard G. Raubenheimer on the occasion of his 65th birthday TwoC2-symmet...