128136-96-9Relevant articles and documents
A New Mode of Operation of Pd-NHC Systems Studied in a Catalytic Mizoroki-Heck Reaction
Astakhov, Alexander V.,Khazipov, Oleg V.,Chernenko, Andrey Yu.,Pasyukov, Dmitry V.,Kashin, Alexey S.,Gordeev, Evgeniy G.,Khrustalev, Victor N.,Chernyshev, Victor M.,Ananikov, Valentine P.
, p. 1981 - 1992 (2017)
Metal complexes bearing N-heterocyclic carbene (NHC) ligands are typically considered the system of choice for homogeneous catalysis with well-defined molecular active species due to their stable metal-ligand framework. A detailed study involving 19 different Pd-NHC complexes with imidazolium, benzimidazolium, and triazolium ligands has been carried out in the present work and revealed a new mode of operation of metal-NHC systems. The catalytic activity of the studied Pd-NHC systems is predominantly determined by the cleavage of the metal-NHC bond, while the catalyst performance is strongly affected by the stabilization of in situ formed metal clusters. In the present study, the formation of Pd nanoparticles was observed from a broad range of metal complexes with NHC ligands under standard Mizoroki-Heck reaction conditions. A mechanistic analysis revealed two different pathways to connect Pd-NHC complexes to "cocktail"-type catalysis: (i) reductive elimination from a Pd(II) intermediate and the release of NHC-containing byproducts and (ii) dissociation of NHC ligands from Pd intermediates. Metal-NHC systems are ubiquitously applied in modern organic synthesis and catalysis, while the new mode of operation revealed in the present study guides catalyst design and opens a variety of novel opportunities. As shown by experimental studies and theoretical calculations, metal clusters and nanoparticles can be readily formed from M-NHC complexes after formation of new M-C or M-H bonds followed by C-NHC or H-NHC coupling. Thus, a combination of a classical molecular mode of operation and a novel cocktail-type mode of operation, described in the present study, may be anticipated as an intrinsic feature of M-NHC catalytic systems.
Platinum(II) 1,2,4-Triazolin-5-ylidene Complexes: Stereoelectronic Influences on Their Catalytic Activity in Hydroelementation Reactions
Dang, Thanh Tuan,Huynh, Han Vinh,Nguyen, Hung Huy,Nguyen, Van Ha
, (2020)
Five platinum(II) 1,2,4-triazolin-5-ylidene (tazy) complexes of the general formula [PtCl2(DMSO)(R-tazy)] (1-5), bearing different N4 substituents (R = Dipp (1), Mes (2), Ph (3), Nap (4), and Bn (5)), have been successfully synthesized. The compounds have
Anti-Plasmodium activity of imidazolium and triazolium salts
Vlahakis, Jason Z.,Lazar, Carmen,Crandall, Ian E.,Szarek, Walter A.
experimental part, p. 6184 - 6196 (2010/09/14)
We have previously reported that tetrazolium salts were both potent and specific inhibitors of Plasmodium replication, and that they appear to interact with a parasite component that is both essential and conserved. The use of tetrazolium salts in vivo is limited by the potential reduction of the tetrazolium ring to form an inactive, neutral acyclic formazan. To address this issue imidazolium and triazolium salts were synthesized and evaluated as Plasmodium inhibitors. Many of the imidazolium and triazolium salts were highly potent with active concentrations in the nanomolar range in Plasmodium falciparum cultures, and specific to Plasmodium with highly favorable therapeutic ratios. The results corroborate our hypothesis that an electron-deficient core is required so that the compound may thereby interact with a negatively charged moiety on the parasite merozoite; the side groups in the compound then form favorable interactions with adjacent parasite components and thereby determine both the potency and selectivity of the compound.
