نتایج جستجو برای: transition elements
تعداد نتایج: 527630 فیلتر نتایج به سال:
Neuroactive compounds can be photoreleased by means of two-photon excitation using a new kind of transition metal-based caged compound.
A range of hierarchically porous (HP) AlPO-5 catalysts, with isomorphously substituted transition metal ions, have been synthesized using an organosilane as a soft template. By employing a range of structural and spectroscopic characterization protocols, the properties of the dopant-substituted species within the HP architectures have been carefully evaluated. The resulting nature of the active...
Polyalkyne and enediyne azamacrocycles are prepared from arenesulfonamides and various alkyne and alkene derivatives either under basic or neutral conditions. The new family of macrocyclic substrates is tested in the [2+2+2] cycloaddition reaction. Several catalysts are used for the cycloisomerization reaction, and their enantioinduction is evaluated as appropriate. The effect of the structural...
Rights: © 1985 American Physical Society (APS). This is the accepted version of the following article: Jena, P. & Nieminen, Risto M. & Puska, M. J. & Manninen, M. 1985. Role of elastic and electronic interacti in trapping of hydrogen by impurities in transition metals. Physical Review B. Volume 31, Issue 12. 7612-7616. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.31.7612, which has been p...
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...
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