10.1002/ejic.201301215
The research focuses on the synthesis, coordination chemistry, and cooperative activation of hydrogen (H2) with ruthenium complexes of proton-responsive sulfonamidophosphorus (METAMORPhos) ligands. The study aims to expand the synthetic scope of these ligands and elucidate design principles for selective formation of specific tautomers, ion pairs, or double condensation products. The METAMORPhos ligands were introduced into the coordination sphere of ruthenium for the first time, enabling exclusive coordination as a monoanionic P,O chelate. The research concluded that these ligands play a role in the heterolytic cleavage of H2, and the proton-responsive character can be tuned to modulate the rate of H2 splitting with these ruthenium species. The chemicals used in the process include various METAMORPhos ligands, ruthenium precursors, and solvents such as toluene, THF, and acetonitrile, as well as reagents like triethylamine and KPF6. The study also provides structural evidence of the complexes through X-ray crystal-structure determination and NMR spectroscopy, highlighting the tunable nature of the PNSO scaffold and its potential applications in catalytic reactions and asymmetric transformations.
10.1007/s00706-013-0925-7
This research presents the development of a heterogeneous palladium catalyst supported by a polymerized functional ionic liquid for the reductive homocoupling of aryl halides. The purpose of the study was to create a recyclable catalyst that could selectively catalyze the formation of biaryls, which are important building blocks in pharmaceuticals and agrochemicals, under mild conditions. The researchers synthesized a homopolymer of 3-(cyanomethyl)-1-vinylimidazolium hexafluorophosphate and used it to support Pd nanoparticles, resulting in the Pd@poly-CN-PF6 catalyst. This catalyst was found to efficiently catalyze the homocoupling reactions of aryl halides in water at 100°C with good yields. The catalyst could be recycled and reused multiple times with only a slight loss in activity, which was attributed to palladium leaching at high temperature and aggregation of palladium nanoparticles. Key chemicals used in the process included 1-vinylimidazole, 2-chloroacetonitrile, potassium hexafluorophosphate, azodiisobutyronitrile (AIBN), and sodium borohydride (NaBH4) for the synthesis of the polymer and the Pd nanoparticles, as well as aryl halides, NaOH, and ascorbic acid in the catalytic reactions.
10.1002/(SICI)1099-0682(199810)1998:10<1563::AID-EJIC1563>3.0.CO;2-P
The research explores the reactivity of ortho-alkenylpyridine ligands (o-AlkPy) with a PdII center in the presence of a base, aiming to extend the scope of palladium-mediated heterocyclisation reactions that form C–N bonds at the allylic position. The study investigates the formation of (?3-allyl)PdII complexes and their subsequent demetallation to yield cationic N-bridgehead heterocycles with stable C–N bonds. Key chemicals include ortho-alkenylpyridines (such as 2-but-3-en-1-ylpyridine and 2-pent-5-en-1-ylpyridine), PdCl2(MeCN)2, and bases like NaOAc and K2CO3. The PdII center plays a crucial role in activating the C–H bond at the allylic position, facilitating the formation of the (?3-allyl)PdII intermediate. Potassium hexafluorophosphate (KPF6) was used to convert the chloride counterions in the cationic heterocycles to PF6–, aiding in the isolation and characterization of the final products. The study concludes that while the formation of stable pyridine–palladium adducts is observed, the yield of the allylic compounds is low, and the formation of the (?3-allyl)PdII complex is limited to specific conditions. The demetallation of these complexes yields cationic N-heterocycles with high regioselectivity, highlighting the potential for intramolecular C–N bond formation in pyridine systems.