124562-04-5Relevant articles and documents
Room temperature Z-selective hydrogenation of alkynes by hemilabile and non-innocent (NNN)Co(ii) catalysts
Gonnade, Rajesh G.,Gouda, Chandrakant,Punji, Benudhar,Sharma, Dipesh M.
, p. 1843 - 1849 (2022/04/07)
Hemilabile and phosphine-free quinolinyl-based NNN-type pincer and non-pincer cobalt complexes were developed for the room temperature catalytic transfer semi-hydrogenation of alkynes to Z-alkenes. Treatment of the quinolinyl-amine ligand, [C9H6N(NH)CH2CH2NEt2] (QNNNCH2NEt2)-H with CoX2 afforded the pincer complexes κ3-(QNNNCH2NEt2)CoX2 (X = Cl, Br), whereas, the quinolinyl-amide ligand, [C9H6N(NH)C(O)CH2NEt2] (QNNNC(O)NEt2)-H gave chelate anionic complexes κ2-(QNN)CoX2(NC(O)HNEt2) (X = Cl, Br). The well-defined anionic non-pincer cobalt complexes efficiently catalyzed the semi-hydrogenation of diverse alkynes to deliver highly chemoselective and stereodivergent Z-alkenes at room temperature. This hydrogenation exhibited broad substrate scope with the tolerance of sensitive functional groups, such as -Cl, -Br, -I, -OH, -NH2, -COOMe, and pyridinyl, employing a stable and user-friendly ammonia borane hydrogen source.
Synthesis, crystal structure, and catalytic activity of bridged-bis(N-heterocyclic carbene) palladium(II) complexes in selective Mizoroki-Heck cross-coupling reactions
El Ali, Bassam,Fettouhi, Mohammed,Iali, Wissam,Mansour, Waseem,Suleiman, Rami
, (2021/08/09)
A series of three 1,3-propanediyl bridged bis(N-heterocyclic carbene)palladium(II) complexes (Pd-BNH1, Pd-BNH2, and Pd-BNH3), with + I effect order of the N-substituents of the ligand (isopropyl > benzyl > methoxyphenyl), was the subject of a spectroscopic, structural, computational and catalytic investigation. The bis(NHC)PdBr2 complexes were evaluated in Mizoroki-Heck coupling reactions of aryl bromides with styrene or acrylate derivatives and showed high catalytic efficiency to produce diarylethenes and cinnamic acid derivatives. The X-ray structure of the most active palladium complex Pd-BNH3 shows that the Pd(II) center is bonded to the two carbon atoms of the bis(N-heterocyclic carbene) and two bromide ligands in cis position, resulting in a distorted square planar geometry. The NMR data of Pd-BNH3 are consistent with a single chair-boat rigid conformer in solution with no dynamic behavior of the 8-membered ring palladacycle in the temperature range 25–120 °C. The catalytic activities of three Pd-bridged bis(NHC) complexes in the Mizoroki-Heck cross-coupling reactions were not found to have a direct correlation with +I effect order of the N-substituents of the ligand. However, a direct correlation was found between the DFT calculated absolute softness of the three complexes with their respective catalytic activity. The highest calculated softness, in the case of Pd-BNH3, is expected to favor the coordination steps of both the soft aryl bromides and alkenes in the Heck catalytic cycle.
Mesoporous silica nanospheres supported atomically precise palladium nanocluster: Highly efficient and recyclable catalysts in the reduction of 4-nitrophenol and Heck reactions
Gao, Taiping,Kang, Zhenlu,Zhao, Yining,Zhou, Yilin
, (2021/12/14)
Atomically precise palladium nanoclusters show great potential applications in the field of catalysis owing to its ultrasmall size and precise structure. This work, we report the mesoporous silica nanoparticles (MSNs) supported [Pd3Cl(PPh3)3(PPh2)2]Cl catalysts (denoted as Pd3Cl/MSNs) for the reduction of 4-nitrophenol and Heck coupling reactions of iodobenzene and styrenes. High uniform MSNs, with average diameter ≈110 nm, were prepared by sol–gel method, followed by Pd nanoclusters immobilization into the pore of MSNs. The MSNs supported Pd nanoclusters were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), and diffuse reflectance optical spectrum. The results indicated that Pd3Cl nanoclusters after immobilized into the pores of MSNs are intact and possess good dispersibility. The catalytic performance of as-prepared nanocomposites was evaluated by the reduction of 4-nitrophenol and Heck reactions. The 4-nitrophenol could be completely conversion to 4-aminophenol within 6?min. Meanwhile, the as-prepared Pd3Cl/MSNs exhibit excellent catalytic performance in the Heck reactions between iodobenzenes and styrenes. The high catalytic activity of Pd3Cl/MSNs could be attributed to the large surface area and unique geometric structure of as-prepared Pd nanoclusters. More importantly, the catalysts could be easily recycled by centrifugation and shows excellent reusability.
