The previously unknown methallylnickel 2-diorganophosphanylphenolates (R=Ph, cHex) were synthesized and found to catalyze the polymerization of ethylene. To explore the potential for ligand-tuning, a variety of P-alkyl- and P-phenyl-2-phosphanylphenols was synthesized and allowed to react with [Ni(cod)(2)] (cod=1,5-cyclooctadiene) or with NiBr(2).DME and NaH. The complexes formed in situ with [Ni(cod)(2)] are generally active as ethylene polymerization catalysts with all the ligands tested, whereas the latter systems are inactive when 2-dialkylphosphanylphenols are applied. M(w) values, ranging from about 1000 to about 100000 g mol(-1), increase for various R(2)P groups in the order R=Ph
Due to its positive effect on flame propagation in the case of a well-defined breakdown, the formation of a large-scale tumble motion is an important goal in engine development. Cycle-to-cycle variations (CCV) in the tumble position and strength however lead to a fluctuating tumble breakdown in space and time and therefore to combustion variations, indicated by CCV of the peak pressure. This work aims at a detailed investigation of the large-scale tumble motion and its interaction with the piston boundary layer during the intake stroke in a state-of-the-art gasoline engine. To allow the validation of the flow near the piston surface obtained by simulation, a new measurement technique called "Flying PIV" is applied. A detailed comparison between experimental and simulation results is carried out as well as an analysis of the obtained flow field. The large-scale tumble motion is investigated based on numerical data of multiple highly resolved intake strokes obtained using scale-resolving simulations. A method to detect the tumble center position within a 3D flow field, as an extension of previously developed 2D and 3D algorithms, is presented and applied. It is then used to investigate the phase-averaged tumble structure, its characteristics in terms of angular velocity and the CCV between the individual intake strokes. Finally, an analysis is presented of the piston boundary layer and how it is influenced by the tumble motion during the final phase of the intake stroke.
Reactions of methallylnickel bromide with 2-R2PC6H4OH 1a,b (R = Ph, cHex) and AgSbF6
furnish methallylnickel phosphinophenol hexafluoroantimonates 2a,b, which are not very
stable and decay in solution at room temperature within an hour (2a) or days (2b) to
tetranuclear nickel complexes 3a,b. The related cationic allylpalladium complex 4a is more
stable. A crystal structure analysis gives evidence of the monomeric nature, the typical
η3-coordination of the allyl group, and the coordination of the phenolic hydroxyl group to
palladium. In solution the OH group is uncoordinated and underlines the hemilabile
character of the phosphinophenol ligands. The allylpalladium phosphinophenol tetrafluoroborate 5a, stable as a solid, slowly decomposes in CDCl3 solution to give a dinuclear complex
6a and in THF/water as the solvent the palladium bis(phosphinophenolate) 7a. Methallylpalladium phosphinophenol acetates 8a,b, existing as phosphinophenolate acetic acid
conjugates, are uncommonly stable and lose the acid on heating in a vacuum without cleavage
of the methallyl group to give neutral methallylpalladium phosphinophenolates 9a,b. The
labile complexes 2a and 2b proved to be highly active single-component catalysts for the
conversion of ethylene to isomer mixtures of butenes, hexenes, and lower amounts of higher
olefins at ambient temperature. The C6 fraction consists mainly of branched and internal
olefins. 5a is less active but converts ethylene on heating under pressure to a mixture of
butenes and smaller amounts of hexenes, while 8 and 9 are inactive.
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