Refernces
10.1021/ja075547t
The research focuses on the synthesis, characterization, and electrochemical behavior of mononuclear ruthenium complexes with vinyl, styryl, and vinylpyrenyl ligands. These complexes were designed to investigate the effects of extending the π-system of the vinyl ligand, manipulating the electron density at the metal atom, and varying the degree of coordinative saturation at the metal atom on bonding, anodic behavior, and the metal versus ligand contribution to the redox-orbitals. The reactants used in the synthesis include ruthenium hydride complexes, terminal alkynes, and various phosphine ligands. The complexes were characterized using spectroscopic methods such as multinuclear NMR, IR, electronic spectroscopy, and X-ray crystallography. Electrochemical analyses, including cyclic voltammetry, IR-spectroelectrochemistry, and ESR spectroscopy, were employed to study the redox behavior and electronic structure of the complexes. The experimental findings were further supported by quantum chemical calculations, which provided insights into the metal versus ligand contributions to the frontier molecular orbitals and the nature of the oxidation processes.
10.1002/anie.201705346
The research focuses on the Perfluoroaryl Azide-Staudinger Reaction, a fast and bioorthogonal chemical reaction between perfluoroaryl azides (PFAAs) and aryl phosphines. The study reports a high reaction rate constant of 18 M-1 s-1 under ambient conditions, leading to the formation of stable iminophosphorane products that are resistant to hydrolysis and aza-Wittig reactions. The experiments involved mixing PFAA 1a and phosphine 2a in acetonitrile, observing the immediate color change and subsequent release of nitrogen gas, and confirming the product structure through single crystal X-ray crystallography. Kinetic analyses were performed to determine the reaction order and rate constants, with solvent effects and substituent effects on the PFAA core and phosphine structures being investigated. The bioorthogonality of the reaction was tested using the N-acetylneuraminic acid metabolic pathway, with PFAA-derivatized sugars being taken up by A549 cells and successfully labeled with phosphine-derivatized fluorescent bovine serum albumin. The experiments utilized techniques such as 1H NMR for monitoring reaction progress, flow cytometry for analyzing cell labeling, and fluorescence microscopy for visualizing labeled cells.
10.1039/b110442j
The study focuses on the synthesis and characterization of ruthenium(II) and ruthenium(IV) complexes containing hemilabile heterodifunctional iminophosphorane-phosphine ligands, which are of interest due to their potential applications in catalysis. The researchers used a series of iminophosphorane-phosphine ligands with different substituents (R = SiMe3, p-C6F4CN, p-C5F4N) to prepare various complexes. These ligands were coordinated to ruthenium centers in different modes, either as monodentate (κ1-P) or bidentate (κ2-P,N) ligands, forming neutral and cationic complexes. The purpose of these chemicals was to investigate the hemilabile properties of the ligands, which refer to their ability to coordinate to a metal center in more than one mode, potentially enhancing the catalytic activity and selectivity of the resulting complexes. The study provides insights into the coordination chemistry of these heterodifunctional ligands and their potential use in homogeneous catalysis.
10.1021/ja01640a072
The study investigates the kinetics of hydrogen exchange between phosphine (PH?) and water containing 3% deuterium. The researchers measured the rate of approach to equilibrium by tracking the uptake of deuterium in phosphine. They found that under conditions where diffusion from the gaseous to the liquid phase is not rate-determining, the fraction of exchange follows the McKay rate law. The study involved using various buffer solutions, including those with acids like mandelic, formic, benzoic, acetic, and trimethylacetic acids, to explore acid catalysis. For base catalysis, sodium carbonate-sodium bicarbonate, disodium phosphate-trisodium phosphate buffers, and unbuffered 0.01 M sodium hydroxide were used. The experiments revealed that the reaction is first order with respect to hydronium ion (H?O?) and hydroxyl ion (OH?) concentration, with rate constants of 3.6 liters/mole second and 0.40 liters/mole second at 27°C, respectively. The study also explored the effects of general acid and base catalysis, inert salt concentration, phosphine pressure, and temperature on the exchange rate. The results provided insights into the acid and base properties of phosphine in aqueous solution, with estimates of the base dissociation constant (KB) and acid dissociation constant (KA) of phosphine.
10.1021/ol048313c
The study presents a novel one-pot method for the synthesis of enantiomerically enriched α-arylated cycloalkanones through the sequential Cu-catalyzed reduction and Pd-catalyzed arylation of silyl enol ethers. The process involves the use of enantiomerically enriched diphenylsilyl enol ethers, prepared from Cu-catalyzed asymmetric conjugate reduction, which are then utilized in the Pd-catalyzed arylation of various aryl bromides. This approach provides an efficient route to α-arylated cycloalkanones with excellent levels of enantiomeric and diastereomeric purity, overcoming the limitations of direct ketone arylation. Key chemicals used include copper (Cu) and palladium (Pd) catalysts, silyl enol ethers, aryl bromides, and various phosphine ligands. The purpose of these chemicals is to facilitate the selective formation of the desired arylation products with high stereochemical control, which are valuable in the synthesis of natural products and pharmaceuticals.
10.1016/S0022-328X(01)01175-5
The research focuses on the synthesis of metallocenes containing tertiary phosphine ligands attached to cyclopentadienyl rings. The purpose of this study was to prepare new metallocene compounds, specifically those containing dimethylphosphinoalkyl-η5-cyclopentadienyl ligands, where the substituents R and R' can be hydrogen or methyl groups. The researchers synthesized a series of metallocene compounds, including those of zirconium, hafnium, manganese, iron, tin, lead, and half-sandwich complexes of rhodium and iridium. Key chemicals used in the synthesis process encompassed various metallocene precursors such as [M(C5Me4CH2PMe2)], where M represents Li+, Na+, or K+, and [Li(C5H4CR'2PMe2)], with R'2 being Me2 or (CH2)5, among others. The conclusions of the research detailed the successful synthesis and characterization of these new metallocene compounds, which have potential applications in catalysis and materials science, and provided insights into their structural and electronic properties through analytical and spectroscopic data.
10.1016/S0022-328X(97)00137-X
The research involves the synthesis, spectroscopic studies, and electron-transfer properties of paramagnetic ruthenium(III) cyclometallated complexes. The purpose of the study was to develop new paramagnetic trivalent ruthenium cyclometallated complexes, specifically focusing on the complex Ru(III)(C,N,O)(N,O)(PPh3) (2) in a mixed phenolato-imine and phosphine ligand environment. The researchers observed the selective activation of the ortho C-H bond of the pendant phenyl ring of the ligand L, leading to the formation of the stable cyclometallated complex 2, which was facilitated by the presence of a methylene (CH2) group in the amine fragment, allowing for the formation of a thermodynamically stable five-membered metallacycle. The study concluded that the presence of phenolato oxygen in combination with the Ru-C bond in complex 2 played a crucial role in stabilizing the ruthenium ion in the paramagnetic trivalent state. Key chemicals used in the process included Ru(PPh3)3Cl2, o-(OH)C6H4C(H)=N-CH2C6H5 (HL), and various solvents and reagents for spectroscopic and electrochemical studies.
10.1021/acscatal.9b04592
The research explores a novel approach to achieve late-stage diversification of complex molecules through a selectivity switch in meta-C–H activation using ruthenium catalysis. The purpose of this study is to develop a method for the controlled functionalization of inert C–H bonds, particularly focusing on switching the selectivity from ortho- to meta-C–H bonds in aromatic compounds, which has been a challenging area in organic synthesis. The researchers utilized key chemicals such as ruthenium(II) complexes, carboxylates, and phosphines to facilitate this selective transformation. They discovered that the cooperative action of carboxylates and phosphines in the presence of ruthenium(II) catalysts enabled a switch in site selectivity, allowing for remote meta-C–H functionalization. This method was demonstrated to be effective with a wide range of substrates, including sensitive biomolecules like nucleosides, lipids, peptides, and fluorescent tags. The study concludes that this approach, supported by mechanistic insights from density functional theory (DFT) calculations and experimental data, provides a robust and versatile platform for the late-stage modification of complex molecules, which could have significant applications in the synthesis of pharmaceuticals and other bioactive compounds.
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F+,
T+,
N
