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Relevant academic research and scientific papers

Exploring electronic and steric effects on the insertion and polymerization reactivity of phosphinesulfonato pdii catalysts

Thirteen different symmetric and asymmetric phosphinesulfonato palladium complexes ([{(X1-Cl)-μ-M}n], M=Na, Li, 1= X(P^O)PdMe) were prepared (see Figure 1). The solid-state structures of the corresponding pyridine or lutidine complexes were determined for (MeO)21-py, (iPrO)21-lut, (MeO,Me2)1-lut, (MeO)31-lut, CF31-lut, and Ph1-lut. The reactivities of the catalysts X1, obtained after chloride abstraction with AgBF4, toward methyl acrylate (MA) were quantified through determination of the rate constants for the first and the consecutive MA insertion and the analysis of β-H and other decomposition products through NMR spectroscopy. Differences in the homo- and copolymerization of ethylene and MA regarding catalyst activity and stability over time, polymer molecular weight, and polar co-monomer incorporation were investigated. DFT calculations were performed on the main insertion steps for both monomers to rationalize the effect of the ligand substitution patterns on the polymerization behaviors of the complexes. Full analysis of the data revealed that: 1) electron-deficient catalysts polymerize with higher activity, but fast deactivation is also observed; 2) the double ortho-substituted catalysts (MeO)21 and (MeO)31 allow very high degrees of MA incorporation at low MA concentrations in the copolymerization; and 3) steric shielding leads to a pronounced increase in polymer molecular weight in the copolymerization. The catalyst properties induced by a given P-aryl (alkyl) moiety were combined effectively in catalysts with two different non-chelating aryl moieties, such as cHexO/(MeO)21, which led to copolymers with significantly increased molecular weights compared to the prototypical MeO1. Catalyst control: The influence of steric and electronic effects on the reactivity of phosphinesulfonato PdII catalysts in polymerization and copolymerization is explored through experimental and DFT methods. A comparison of thirteen different X(P O)PdMe catalysts ((P O)= κ2-P,O-R1R2PC6H 4SO2O; see figure) reveals insights into the catalyst reactivity toward methyl acrylate and ethylene, their influence on the polymer microstructure, and the decomposition pathways. The unraveling of these relations provides guidelines for a directed choice of catalysts. Copyright

Single site palladium catalyst complexes

Catalyst structures comprising a single palladium metal center and a substituted tri-arylphosphine ligand. Also disclosed are methods of making and using the catalyst structures to facilitate polymerization reactions and Heck coupling reactions.

Process for preparing ortho-substituted phenylphosphine ligands

Ligand synthesis methods for the preparation of ligands having the formula wherein Q is selected from phosphorus, arsenic and antimony; wherein X 1 , X 2 and X 3 are carbon anions; and, wherein R 15 is selected from -SO 3 , -SO 2 N(R 18 ), -CO 2 , -PO 3 , -AsO 3 , -SiO 2 , -C(CF 3 ) 2 O; where R 18 is selected from a hydrogen, a halogen, a hydrocarbyl group and a substituted hydrocarbyl group, are disclosed. Also disclosed are methods of complexing the ligands with late transition metals to form catalyst complexes that catalyze polymerization reactions and/or Heck coupling reactions.