Refernces
10.1016/j.jorganchem.2007.12.033
The research focuses on the synthesis, structure, and reactions of novel j3S,C,S-pincer palladium complexes containing a 3,5-pyridinediyl unit. The cyclopalladation of 3,5-bis(diphenylphosphinothioyl)pyridine led to the formation of new j3S,C,S-pincer palladium complexes with a p-bond between Pd and the 4C of the centered 3,5-pyridinediyl unit. The study utilized the quaternization and complexation ability of the pyridine imine nitrogen (Npy) atom to synthesize various new pincer-type complexes, including hetero-binuclear complexes. The experiments involved Pd-catalyzed aryl phosphination of 3,5-dibromopyridine with diphenylphosphine, followed by sulfurization to obtain the ligand. Further reactions with PdCl2(PhCN)2 and sodium acetate yielded the pincer palladium complex, which was then subjected to quaternization and complexation reactions. The chemical structures were confirmed using NMR, FAB-mass spectroscopy, elemental analysis, and X-ray crystallography. The study also investigated the UV–Vis absorption spectra of the complexes.
10.1021/jo800665t
The study focuses on the synthesis of mono- and diphosphine ligands based on the 4,4′-bisquinolone framework, known as BIQUIP ligands, which are designed for use in asymmetric catalysis. These ligands were generated through microwave-assisted palladium-catalyzed carbon-phosphorus cross-coupling reactions using heteroaryl bromides and diphenylphosphine as substrates. The aim was to create ligands with tunable electronic properties and potential hemilabile coordinating abilities, which could enhance the efficiency and selectivity of catalytic processes. Key chemicals used in the study include 3-bromo- and 3,3′-dibromobisquinolones as starting materials, N-bromosuccinimide (NBS) for bromination, diphenylphosphine (Ph2PH) for the cross-coupling reaction, and Herrmann’s palladacycle as a catalyst. The synthesized ligands are expected to offer unique impacts on the electronic properties of the phosphine ligators due to the presence of the cyclic enamide system in the quinolone moiety, and they serve to expand the range of available ligands for asymmetric catalysis.
10.1016/0022-328X(93)83012-K
The study presented in the "Journal of Organometallic Chemistry" focuses on the synthesis, properties, and structural analysis of N,N-functionalized bis(amino)carbene molybdenum(0) carbonyl complexes. The researchers prepared the complexes by treating 1,2-bis(y-diphenylphosphinopropylaminojethane) with specific reagents, yielding electron-rich enetetramine ligands. These ligands were then used to form carbenemolybdenum title compounds, which were characterized by various spectroscopic techniques and X-ray crystallography. The study revealed that one of the compounds exhibited a rare example of a metal complex with both carbene- and n*-alkene-ligation. Additionally, the researchers investigated the reactivity of the complexes, including their reactions with 13CO, PEt3, and under thermal conditions, providing insights into the potential of these complexes in catalytic alkene metathesis reactions.
10.1016/j.jcat.2018.06.012
The research focuses on the structural elucidation of rhodium (Rh) complexes derived from RhCl(PPh3)3, immobilized on surface-functionalized SBA-15 silica, which is functionalized with primary amine, secondary amine, or diphenylphosphine groups. The study aims to understand the local structures of these immobilized Rh complexes and their catalytic performance in C-heteroatom (S, O) bond formation reactions, specifically hydrothiolation and hydrosulfonation. The experiments involved the preparation of immobilized Rh complexes through covalent bonding with different functional groups on the silica surface, which was characterized using a variety of techniques including XRD, HR-TEM, multinuclear solid-state NMR, XPS, and Rh K-edge EXAFS. The catalytic performance of these complexes was evaluated by adding alkynes with thiols and sulfonic acids under mild reaction conditions, with the focus on activity, regio- and stereoselectivity. The analyses used to determine the structure and performance of the catalysts included nitrogen adsorption isotherms, low-angle XRD, HR-TEM, solid-state NMR, XPS, and EXAFS, which collectively provided insights into the chemical environment and local structure of the surface-supported Rh complexes.
10.1002/chem.201101529
The research focuses on the development of a novel synthetic methodology for the preparation of C1-symmetric bis(diphenylphosphino)biphenyl ligands, which are crucial in asymmetric catalysis. The study aimed to overcome the challenges associated with the synthesis of these ligands, particularly the undesired intramolecular cyclization leading to phosphafluorene formation. The researchers successfully developed a palladium-catalyzed C–P coupling reaction that does not require additional ligands and avoids the formation of phosphafluorene in most cases. This method allows for the rapid synthesis of a variety of substituted ortho,ortho'-bis(diphenylphosphino)biphenyls in moderate-to-excellent yields and significantly reduced reaction times compared to previous methods. Key chemicals used in the process include ortho,ortho’-dihalobiphenyl precursors, diphenylphosphine (HPPh2), palladium acetate (Pd(OAc)2) as the catalyst, potassium acetate (KOAc) as the base, and N,N-dimethylacetamide (DMA) as the solvent. The study's conclusions open new pathways for the synthesis of more complex diphosphines based on C1- or C2-symmetric biaryl scaffolds and has implications for the direct synthesis of enantiomerically pure C1-symmetric biaryl-based diphosphines.
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