نتایج جستجو برای: heterocyclic carbenes

تعداد نتایج: 9891  

Journal: :Chemistry – An Asian Journal 2007

Journal: :Chemical Communications 2021

Cyclotriarsanes are rare and described herein is a scalable synthetic protocol towards aryl-substituted derivatives. Their reactivity [Cp2Ti(C2(SiMe3)2)], affording titanocene diarsene complexes, N-heterocyclic carbenes (NHCs) discussed.

2017
Sunit Hazra Yoichi Hoshimoto Sensuke Ogoshi

This article discusses the concept of N-heterocyclic carbenes (NHCs) equipped with more than one functional moiety, which allows using these NHCs for multiple purposes. A pioneering example for such NHCs is N-phosphine oxide-substituted imidazolylidenes (PoxIms), and their synthesis and strategic use are highlighted. The utility of PoxIms by far exceeds the conventional use as multidentate liga...

Journal: :Organic & biomolecular chemistry 2013
Stuart M Leckie T Bruce Brown David Pryde Tomas Lebl Alexandra M Z Slawin Andrew D Smith

Chiral N-heterocyclic carbenes (NHCs) promote the asymmetric formal [4 + 2] cycloaddition of alkylarylketenes with β,γ-unsaturated α-ketocarboxylic esters and amides. Divergent diastereoselectivity is observed in this process, with γ-aryl-β,γ-unsaturated α-ketocarboxylic esters and amides giving preferentially syn-dihydropyranones (up to 68 : 32 dr syn : anti, up to 98% ee), while γ-alkyl-deriv...

Journal: :Chemical communications 2014
Christian Richter Kira Schaepe Frank Glorius Bart Jan Ravoo

N-heterocyclic carbenes (NHCs) represent a leading class of ligands in organometallic chemistry, but have been rarely exploited as stabilizers for metal nanoparticles (NPs). We report the first example of NHC stabilized Pd-NPs that demonstrate long term stability. These NHC Pd-NPs were synthesized by a facile ligand exchange protocol using rationally designed long chained NHCs (LC-NHCs). Furthe...

2010
Marion Heckenroth

N-heterocyclic carbenes (NHCs), typically derived from imidazolium salts, have provided highly powerful ligands for catalysis. Recently, abnormal C4 bonding rather than normal C2 bonding has been discovered as a new carbene bonding mode. We were interested in comparing the consequences of these two bonding modes on the metal center. Therefore we synthesized related palladium complexes 1 and 2 c...

Journal: :Karadeniz fen bilimleri dergisi 2023

N-heterocyclic carbenes have initially attracted great attention of the chemists in consequence their catalytic activity. The favorable results were also obtained bioactivity studies for carbenes, and transition metal complexes following years. Theoretical methods deliver beneficial data about several activities molecules. One them is frontier orbital analysis, which supplies reactivity Another...

Journal: :Chemical communications 2010
Dimitri Hirsch-Weil Khalil A Abboud Sukwon Hong

C(1)-symmetric isoquinoline-based chiral diaminocarbene ligands (MIQ) have been developed to block three quadrants of the metal coordination sphere, complementing C(2)-symmetric biisoquinoline-based ligands (BIQ). MIQ-Cu complexes catalyzed conjugate borylation of various α,β-unsaturated amides in good yields (82-99%) and enantioselectivities (75-87% ee).

Journal: :Dalton transactions 2016
Kai Schwedtmann Robin Schoemaker Felix Hennersdorf Antonio Bauzá Antonio Frontera Robert Weiss Jan J Weigand

2-Phosphanyl-substituted imidazolium salts 2-PR2(4,5-Cl-Im)[OTf] (9a,b[OTf]) (4,5-Cl-Im = 4,5-dichloro-1,3-bis(2,6-di-isopropylphenyl)-imidazolium) (a: R = Cy, b: R = Ph) are prepared from the reaction of R2PCl (R = Cy, Ph) with NHC 8 (4,5-dichloro-1,3-bis(2,6-di-isopropylphenyl)-imidazolin-2-ylidene) in the presence of Me3SiOTf. 5-Phospanyl-substituted imidazolium salts 5-PR2(2,4-Cl-Im)[OTf] (...

Journal: :Inorganic chemistry 2004
Seung Uk Son Kang Hyun Park Young-Shin Lee Bo Yun Kim Cheol Ho Choi Myoung Soo Lah Yun Hee Jang Du-Jeon Jang Young Keun Chung

Novel complexes 1 and 2 based on N-heterocyclic carbenes, which are analogous to Ru(bpy)(3)(2+) and Ru(terpy)(2)(2+), respectively, were synthesized. The complex, which is analogous to Ru(terpy)(2)(2+), exhibited promising photoluminescence properties with a long lifetime of 820 ns in acetonitrile and 3100 ns in water at room temperature, respectively. In addition, ab initio calculations were c...

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