Search results for "Alkali metal"
showing 10 items of 190 documents
Electron Transfer and Conformational Interconversions in 1, n ‐Diphenylpolyenes
1988
1,4-Diphenylbutadiene (1), 1,6-diphenylhexatriene (2), and 1,8-diphenylocatatetraene (3) are reduced with alkali metals and the resulting paramagnetic monoanions and diamagnetic dianions characterized by ESR and (1H-, 13C-)NMR spectroscopy, respectively. The stereodynamic behavior of the ions is studied as a function of chain length, charge, and counterion. The reduction of 1, 2, and 3 serves as a model experiment for the doping of extended linear polyenes (polyacetylenes). Elektronenubertragungen und Konformationsanderungen in 1,n-Diphenylpolyenen 1,4-Diphenylbutadien (1), 1,6-Diphenylhexatrien (2) und 1,8-Diphenyloctatetraen (3) werden mit Alkalimetallen reduziert, und die resultierenden …
2D and 3D Anilato-Based Heterometallic M(I)M(III) Lattices: The Missing Link
2015
The similar bis-bidentate coordination mode of oxalato and anilato-based ligands is exploited here to create the first examples of 2D and 3D heterometallic lattices based on anilato ligands combining M(I) and a M(III) ions, phases already observed with oxalato but unknown with anilato-type ligands. These lattices are prepared with alkaline metal ions and magnetic chiral tris(anilato)metalate molecular building blocks: [M(III)(C6O4X2)3](3-) (M(III) = Fe and Cr; X = Cl and Br; (C6O4X2)(2-) = dianion of the 3,6-disubstituted derivatives of 2,5-dihydroxy-1,4-benzoquinone, H4C6O4). The new compounds include two very similar 2D lattices formulated as (PBu3Me)2[NaCr(C6O4Br2)3] (1) and (PPh3Et)2[KF…
Homo‐ and Heteroleptic Hypersilylcuprates — Valuable Reagents for the Synthesis of Molecular Compounds with a Cu−Si Bond
2003
Unsolvated hypersilanides MHyp [Hyp = Si(SiMe3)(3)] of the heavier alkali metals (M-I = Na, K, Cs) react with copper tert-butoxide in toluene to yield crystalline heteroleptic cuprates [M-I(toluene)][tBuOCuHyp]. These cuprates proved to be valuable sources for pure hypersilylcopper and other cuprates bearing hypersilyl ligands such as the di(hypersilyl)cuprates M-I[CuHyp(2)]((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).
Die Stereochemie der Spaltung chiraler acyclischer quartärer Phosphoniumsalze zu tertiären Phosphinoxiden mit Alkalialkoholat
1975
Die beobachtete Brutto-Stereochemie der Spaltung chiraler acyclischer quartarer Phosphoniumsalze 1–5 zu tertiaren Phosphinoxiden 6–10 mittels Natriumathylat ist — mit einer Ausnahme — prinzipiell die gleiche wie bei der Spaltung der betreffenden Salze mit Natrium-hydroxid. Die Stereoselektivitat ist dagegen bei der Spaltung mit Alkoholat meist deutlich geringer als bei der Reaktion mit Natriumhydroxid. Stereochemistry of the Alkali Alcoholate-induced Fission of Chiral Acyclic Quaternary Phosphonium Salts to Tertiary Phosphine Oxides The stereochemical course of the sodium ethanolate-induced fission of chiral acyclic quaternary phosphonium salts 1–5 to tertiary phosphine oxides 6–10 is (with…
Conductance in homomorphous solvents: Tetrabutylammonium salts and alkali picrates in butyrolactone-sulfolane mixtures
1983
Conductance measurements are reported for LiPi, NaPi, KPi, RbPi, CsPi, Bu4NPi, Bu4NBr, Bu4NClO4, Bu4NNO3, and Bu4NBBu4 at 25°C in γ-butyrolactone-sulfolane mixtures. In these mixtures of solvents that are practically homomorphous, isodielectic and with comparable dipole moments, the ion pair association and ionic mobilities of large ions conform to the expectations of the primitive model. Electrolytes containing lithium or sodium ions show anomalies indicating that other factors besides shape, dipole moment, and polarizability of the solvent molecules are involved in the association and transport processes of these ions.
Theoretical EHT study of oxidative coupling of methane on pure MgO and MgO doped with Li and Na
1991
Abstract On the basis of Extended Huckel Theory, empirical studies on the oxidative coupling of methane with MgO pure and MgO doped with Li and Na are presented. The results obtained from the two-dimensional energy surfaces calculated for the interaction between linear clusters of these oxides and the methane molecule show a qualitative agreement with the experimental behaviour reported for these catalysts. The calculated activation energy barriers are in accord with the relative activities of these oxides (Li/MgO > Na/ MgO > MgO) and are of the same order of magnitude as the experimentally determined activation energies.
Density functional theory based screening of ternary alkali-transition metal borohydrides: a computational material design project.
2009
We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K M1; and 1 alkali, alkaline earth or 3d / 4d transition metal atom M2 plus two to five BH4 groups, i.e., M1M2BH42‐5, using a number of model structures with trigonal, tetrahedral, octahedral, and free coordination of the metal borohydride complexes. Of the over 700 investigated structures, about 20 were predicted to form potentially stable alloys with promising decomposition energies. The M1Al/ Mn/ FeBH44, Li/ NaZnBH43, and Na/ KNi/ CoBH43 alloys are …
Weak alkali and alkaline earth metal complexes of low molecular weight ligands in aqueous solution
2008
This work is aimed at reviewing the chemical literature dealing with thermodynamic aspects of the weak complex formation (species with log K values less than about 3) between alkali and alkaline earth metal ions with low molecular weight inorganic and organic ligands in aqueous solution. The following ligands (up to hexavalent anions) were examined in detail: (i) hydroxide, chloride, sulfate, carbonate and phosphate as inorganic, and (ii) carboxylates, amines, amino acids, complexones and nucleotides as organic ligands. The paper also identifies the main reasons responsible for the dispersion of the stability data on ion pairs in the literature. When possible, the trend of stability for the…
Production of ionic and atomic beams of alkaline elements
1980
Abstract An on-line mass spectrometer has been developed and used to perform atomic and nuclear spectroscopy on long series of alkali isotopes including nuclei far from stability. The apparatus was on-line either to the ISOLDE mass separator or directly to the PS, proton beam. In the case of atomic spectroscopy, a thermal atomic beam is needed. As ISOLDE delivers 60 keV ions, a high efficiency “ion-to-atom coverter” has been developed. In all cases, an “ionizer” is required to produce 10 keV ions for the ion source of the mass spectrometer. These two special devices are described, their efficiency and the consequent delay times discussed. The different targets which have been developed for …
MAGNETIC COUPLING OF ALKALI AND RARE-GAS FILMS ADSORBED ON A FERROMAGNETIC SURFACE
2002
The observation of magnetic circular dichroism in the angular distribution of photoelectrons (MCDAD) from alkali and rare-gas films adsorbed on a thin remanently magnetized Co layer is reported. The observation of an antisymmetric MCDAD near normal emission for Co(0001)–Cs 5p semi core level is shown. The reversed magnetization leads to a mirror-image-like distribution. The second system under investigation, physisorbed Co(0001)–Xe 5p, does not give such an but shows significant differences in the MCDAD signal for both directions of magnetization, in particular in the |mj| substates of the p3/2 level. A magnetic coupling between Xe and Co is evident when we take results of spin-resolved ph…