نتایج جستجو برای: heterocyclic carbenes
تعداد نتایج: 9891 فیلتر نتایج به سال:
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.
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...
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...
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...
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...
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...
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).
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] (...
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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