نتایج جستجو برای: inner transition elements
تعداد نتایج: 602988 فیلتر نتایج به سال:
The activation and use of oxygen for the oxidation and functionalization of organic substrates are among the most important reactions in a chemist's toolbox. Nevertheless, despite the vast literature on catalytic oxidation, the phenomenon of autoxidation, an ever-present background reaction that occurs in virtually every oxidation process, is often neglected. In contrast, autoxidation can affec...
Structures and stabilities of a new family of multi-decker tricarbonyl-bridged sandwich complexes of transition metals (Cr, Mn, Fe) have been studied using DFT B3LYP/6-311+G(df,p) calculations. Stable structures satisfy the (12n + 6) electron-counting rule, where n is the number of metal atoms. Lengthening of the molecular chains is accompanied by growth of aromaticity of the inner basal cycles...
Transition metal-catalyzed reactions are generally used for carbon-carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon-heteroatom bond formation in pyrazines are known. This perspective reviews recent progress in the field of transition metal-catalyzed ...
Asymptotics-based configuration-interaction (CI) methods [G. Friesecke and B. D. Goddard, Multiscale Model. Simul. 7, 1876 (2009)] are a class of CI methods for atoms which reproduce, at fixed finite subspace dimension, the exact Schrödinger eigenstates in the limit of fixed electron number and large nuclear charge. Here we develop, implement, and apply to 3d transition metal atoms an efficient...
Benzhydryl protection of primary and secondary alcohols has been reported previously via reaction with metal alcoholates. Our aim was to find generally useful and very mild conditions for the alcoholic protection and deprotection of nucleosides with the diphenylmethyl group. This was accomplished for some pyrimidine nucleosides using PdCl₂ as the transition metal catalyst, and with optimization...
The extraordinary electronic structures of monolayer transition metal dichalcogenides, such as the spin-valley-coupled band edges, have sparked great interest for potential spintronic and valleytronic applications based on these two-dimensional materials. In this work, we report the experimental observation of quasi-particle interference patterns in monolayer WSe2 using low-temperature scanning...
One of the determining factors in whether single-molecule magnets (SMMs) may be used as the smallest component of data storage, is the size of the barrier to reversal of the magnetisation, Ueff. This physical quantity depends on the magnitude of the magnetic anisotropy of a complex and the size of its spin ground state. In recent years, there has been a growing focus on maximising the anisotrop...
Having access to mild and operationally simple techniques for attaining carbohydrate targets will be necessary to facilitate advancement in biological, medicinal, and pharmacological research. Even with the abundance of elegant reports for generating glycosidic linkages, stereoselective construction of α- and β-oligosaccharides and glycoconjugates is by no means trivial. In an era where expande...
The first transition metal catalyzed asymmetric carboalkoxylation reaction of propargyl esters is described. The (R)-MeO-DTBM-BIPHEP(AuCl)(2)-catalyzed reactions allow for the construction of benzopyrans containing quaternary stereocenters with excellent enantioselectivity. Experimental evidence supports a mechanism proceeding via the generation of a stabilized carbocation from an allylic oxoni...
Two-dimensional transition metal dichalcogenides (TMDCs) have spurred excitement for potential applications in optoelectronic and valleytronic devices; however, the origin of the dynamics of excitons, trions, and other localized states in these low dimensional materials is not well-understood. Here, we experimentally probed the dynamics of excitonic states in monolayer WSe2 by investigating the...
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