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Electronic Tuning (electronic + tuning)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Electronic Tuning of Nickel-Based Bis(dicarbollide) Redox Shuttles in Dye-Sensitized Solar Cells,

ANGEWANDTE CHEMIE, Issue 31 2010
Alexander
Redox nach Belieben: Die Synthese einer Reihe neuer borfunktionalisierter NiIII/NiIV -Bis(dicarbollid)-Cluster führt zu einer Familie von robusten und justierbaren Redox-Shuttles. Dies bietet eine Möglichkeit zur gezielten Steuerung der Redoxeigenschaften farbstoffsensibilisierter Solarzellen, was in außergewöhnlich hohen Leerlaufspannungen resultierte. [source]

Chemoenzymatic Synthesis and Application of Bicyclo[2.2.2]octadiene Ligands: Increased Efficiency in Rhodium-Catalyzed Asymmetric Conjugate Additions by Electronic Tuning,

ANGEWANDTE CHEMIE, Issue 15 2010
Yunfei Luo
Liganden nach Wunsch: Eine Serie von bicyclischen 1,4-Dimethyl[2.2.2]dien-Liganden mit flexibler Substitution in der Brücke ist durch Lipase-katalysierte Racematspaltung mit anschließender sechsstufiger Reaktionssequenz zugänglich. Die Methylgruppen am Brückenkopf führen zu einer erhöhten Reaktionseffizienz, wodurch in der Titelreaktion weniger Arylboronsäure nötig ist. [source]

ChemInform Abstract: Chemoenzymatic Synthesis and Application of Bicyclo[2.2.2]octadiene Ligands: Increased Efficiency in Rhodium-Catalyzed Asymmetric Conjugate Additions by Electronic Tuning.

CHEMINFORM, Issue 34 2010
Yunfei Luo
Abstract A new series of 1,4-disubstituted 2,5-diaryl bicyclo[2.2.2]octadienes are prepared. [source]

Synthesis, Characterization, and Protonation Reactions of Ar-BIAN and Ar-BICAT Diimine Platinum Diphenyl Complexes

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2010
Jerome Parmene
Abstract PtII diphenyl complexes (N,N)PtPh2 [N,N = diimines Ar,N=C(An)C=N,Ar with Ar = substituted aryl groups] have been prepared and characterized by 1H, 13C, and 195Pt NMR spectroscopy. The 195Pt NMR spectroscopic data establish the electronic influence exerted by substituents at the backbone of the diimine ligand system to the metal center. When compared to diimines Ar,N=CMe,CMe=N,Ar, the electron-withdrawing ability of the Ar-BIAN ligand and the electron-donating ability of the O,O-heterocyclic Ar-BICAT systems are demonstrated. Trends in 195Pt NMR chemical shifts suggest that electronic tuning of the metal center is better achieved through variations of the diimine backbone substituents rather than variation of the substituents at the N-Aryl groups. Protonation of (N,N)PtPh2 in dichloromethane/acetonitrile at ,78 °C furnishes the corresponding PtIV hydrides (N,N)PtPh2H(NCMe)+. The PtIV hydrides liberate benzene with the formation of (N,N)PtPh(NCMe)+ when the temperature is raised. A second protonation and rapid benzene elimination produces the dicationic PtII species (N,N)Pt(NCMe)22+ at approximately 50 °C. Protonation of (N,N)PtPh2 in the absence of acetonitrile results in the clean formation of (N,N)PtPh(,2 -C6H6)+ at temperatures that depend on the steric hindrance provided by the alkyl substituents at the diimine N-aryl groups. These findings support the notion that the metal is the kinetically preferred site of protonation. The results qualitatively agree with a recent mechanistic study of protonation-induced reactions of (diimine)PtPh2 complexes that bear simple methyl substituents at the diimine backbone. Several compounds have been crystallographically characterized. All complexes have the expected square planar environment at the metal. Modest variations in the metric parameters suggest that the Ar-BICAT system has a weaker trans influence than the Ar-BIAN and Ar-DAB systems. [source]