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Reduction Waves (reduction + wave)

Distribution by Scientific Domains

Chemistry	100%

Selected Abstracts

Chiral Ruthenium,Allenylidene Complexes That Bear a Fullerene Cyclopentadienyl Ligand: Synthesis, Characterization, and Remote Chirality Transfer

CHEMISTRY - AN ASIAN JOURNAL, Issue 3 2007
Yu-Wu Zhong Dr.
Abstract Ruthenium complexes that bear both a fullerene and an allenylidene ligand, [Ru(C60Me5)((R)-prophos)=CCCR1R2]PF6 (prophos=1,2-bis(diphenylphosphanyl)propane), were prepared by the reaction of [Ru(C60Me5)Cl((R)-prophos)] and a propargyl alcohol in better than 90,% yields, and characterized by 1H, 13C, and 31P,NMR, IR, and UV/Vis/NIR spectroscopy and MS. Cyclic voltammograms of these complexes showed one reversible or irreversible reduction wave due to the allenylidene part, and two reversible reduction waves due to the fullerene core. Nucleophilic addition of RMgBr or RLi proceeded regioselectively at the distal carbon atom of the allenylidene array. The reaction took place with a 60:40,95:5 level of diastereoselectivity with respect to the original chirality in the (R)-prophos ligand, which is located six atoms away from the electrophilic carbon center. [source]

A Rigid Molecular Scaffold Affixing a (Polypyridine)ruthenium(II)- and a Nickel(II)-Containing Complex: Spectroscopic Evidence for a Weakly Coupled Bichromophoric System

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2003
Yann Pellegrin
Abstract The synthesis of DppztBuSalH2 (7), a rigid conjugated ditopic ligand containing a Dppz (dipyrido[3,2- a:2,,3,- c]phenazine) skeleton and a salophen-type chelate, is reported. The complexes DppztBuSalNi (10), [Ru(bpy)2(DppztBuSalH2)]2+ (11), and [Ru(bpy)2(DppztBuSalNi)]2+ (12) have been prepared and characterised using common spectroscopic methods. Electrochemical, UV/Vis spectroelectrochemical and EPR studies were conducted on compounds 7, 10, 11, and 12. The singly reduced radical forms of 7 and 10 can be generated electrochemically, with the lone electron located on the low-lying phenazine ,*-molecular orbital. Complexes 11 and 12 show several reduction waves and electronic and EPR data obtained for the electrogenerated singly reduced species show them to be closely related to the radical species 7·, and 10·,, respectively. The presence of nickel(II) in compound 12 renders the addition of the second electron on the phenazine group reversible. Both 11 and 12 show common features on the cathodic side of their cyclic voltammograms, with reversible one-electron ruthenium-centred oxidation. An additional low-potential reversible-oxidation wave is observed for 12, and this is ascribed to oxidation of the nickel(II) ion. The combined spectroscopic data best describe the ruthenium-containing complexes as weakly coupled bichromophoric systems. Photophysical studies attest to the formation of a charge-separated state for 11, whereas a strong quenching is detected for 12. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Electrochemical Properties and Computations of Stable Radicals of the Heavy Group,14 Elements (Si, Ge, and Sn)

CHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2009
James
Abstract A series of stable radicals centered on persilyl-substituted heavy Group,14 elements, (tBu2MeSi)3E. (E=Si, Ge, Sn), was studied by cyclic voltammetry in different solvents to determine their first oxidation and reduction potentials and to compare their ease of oxidation and reduction with known experimental and computed ionization energies (Ei) and electron affinities (Eea), respectively. It has been observed that all of the first oxidation and reduction potentials for the three radicals studied are irreversible in o -dichlorobenzene (o -DCB), whereas the reduction waves are quasi-reversible in THF. A good correlation has been found between measured oxidation potentials and ionization energy values, but no correlation between reduction potentials and electron affinity values was found, probably due to kinetic and surface effects. [source]