Nuclear magnetic resonance alkali metal

Solutions of alkali metals in liquid ammonia have been studied by many techniques. These include electrical conductivity, magnetic susceptibility, nuclear magnetic resonance (NMR), volume expansion, spectroscopy (visible and infrared), and other techniques. The data obtained indicate that the metals dissolve with ionization and that the metal ion and electron are solvated. Several simultaneous equilibria have been postulated to explain the unique properties of the solutions. These are generally represented as follows ... 

The measurement of complexation has been accomplished by a variety of techniques. For alkali metal cations with simple crowns, calorimetric and ion selective electrodes have been, by far, the most common. Nuclear magnetic resonance (NMR) methods have also been used commonly and increasingly as the receptors and their substrates become more complex. 

Ill] A. I. Popov The Use of Alkali Metal Nuclear Magnetic Resonance in the Study of Solvation and Complexation of Alkali Metal Ions, in J. F. Coetzee and C. D. Ritchie (eds.) Solute-Solvent Interactions, Dekker, New York, London, 1976, Vol. 2, p. 271ff. A. I. Popov Alkali Metal, Mag-nesium-25, and Silver-109 NMR Studies of Complex Compounds in Nonaqueous Solvents, in G. Mamantov (ed.) Characterization of Solutes in Non-Aqueous Solvents, Plenum Publ. Corp., New York, 1978. [111a] P. Laszlo Kernresonanzspektroskopie mit Natrium-23, Angew. Chem. 90, 271 (1978) Angew. Chem. Int. Ed. Engl. 17, 254 (1978). [112] N. A. Matwiyoff, P. E. Darley, and W. 

The results of nuclear magnetic resonance (NMR) measurements on alkali fullerides K cC o reported. The NMR spectra demonstrate that material with 0 < X < 3 is in fact a two-phase system at equilibrium, with x = 0 and x = 3. NMR lineshapes indicate that C o Ions rotate rapidly in the KsC q phase at 300 K, while 50 ions in the insulating KaC o phase are static on the time scale of the lineshape measurement. The temperature dependence of the spin-lattice relaxation rate in the normal state of is found to be characteristic of a metal, indicating the... 

Krogh-Moe (1958, 1960) concluded that the change in the coordination number of boron from 3 to 4 takes place up to a content of 33 mole % of alkali metal oxide, which corresponds to the maximum concentration of 50% of four-coordinated boron. This assumption has been explicitly experimentally confirmed using the measurements of nuclear magnetic resonance carried out by Silver and Bray (1958) and Bray and O Keefe (1963). These authors found out that within the concentration range of x = 0-30 mole % of alkali metal oxide the concentration of four-coordinated boron, N, may be quite accurately expressed by the relation... 

Nuclear Magnetic Resonance (NMR). Alkali metal NMR is of interest because it is a sensitive probe to monitor the immediate chemical environment and the mobility of alkali metal ions in aqueous or nonaqueous solvents. Sodium-23 NMR method (26.46 MH ) was first employed by Komoroskl and Mauritz (33) to study cation binding in a perfluorinated sodium salt membrane (EW=1100) as a function of water content and temperature. A profound chemical shift and an increase in line width were observed with decreasing water content. These effects reversed as temperature increased. It was interpreted that as the amount of water or temperature is reduced, a larger fraction of sodium ions is bound to the membrane at any given instant. This causes the observed line width and the chemical shift to approach the values for the completely bound species. 

Bribre, K.M. Detellier, C. Metal interchange of crown ether-alkali metal cation complexes in solution. Li Nuclear magnetic resonance study of the exchange kinetics of lithium 15-crown-5 and lithium monobenzo-15-crown-5 in nitromethane. J. Phys. Chem. 1992. 96 (5), 2185-2189. 

R79 G. Wu and J. Zhu, Nuclear Magnetic Resonance Studies of Alkali Metal Ions in Organic and Biological Solids , Prog. Nucl. Magn. Reson. Spectrosc., [online computer file], 2012, 61, 1. 

The nuclear magnetic resonance spectroscopy is one of the techniques that are widely used for researches into intercalated graphite (Estrade-Szwarckopf 1985). Here, the major part of experimental results has been achieved for graphite intercalated with alkali metals since nuclei of isotopes Li, Ru, and Cs are known to have a magnetic moment differing from zero, which allows one to make a record of them in NMR spectra. In the case of graphite intercalated with potassium, it proved possible to record well-resolved spectra for samples with various concentrations of... 

Nuclear magnetic resonance studies are necessary in other metal-ammonia solutions besides sodium to see whether the observed small proton Knight Shift in sodium-ammonia solutions is an universal property of the solutions or not. Also careful Overhauser effect studies of both the metal nucleus as well as the and nuclei are necessary in a number of alkali metal-ammonia solutions in view of Carver and Slichter s measurements on sodium-ammonia solutions. 

The pulse Fourier transform approach to magnetic resonance spectroscopy has been extensively developed and successfully applied to systems of one-half spin and their mutual interactions. But resonance spectroscopy of spin systems with the higher half- and integer spin quantum numbers is commonplace, for example, in the case of alkali metal nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) of transition metal compounds involving multi-quantum transitions. Similarly, magnetic resonance at zero field entails the observation of multi-quantum transitions. 

Mota de Freitas D (1993) Alkali metal nuclear magnetic resonance. Methods in Enzymology 117-. 78-106. 

In an NMR experiment, transitions are induced between these levels with radio frequency fields applied at or near the resonant frequency a o (Abragam, 1961 Slichter, 1990). The alkali metals are good candidates for NMR experiments because there are a number of abundant, stable nuclear isotopes, Li, Li, Na, Rb, Rb, and Cs. The exception is potassium the isotope possesses only a weak magnetic moment and occurs with low natural abundance. 

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