Benzene carbon-deuterium bond activation by free vanadium cluster cations

Abstract

aqueous phase on the organic liquid, however, has not been commented upon nor rigorously assessed. To a first approximation, one assumes that the "interfacial" organic liquid behavior parallels that of the bulk phase. How do these observations compare to the phospholipid bilayer-water interface?Consider first the acyl chain region. In the center of a bilayer, e.g., composed of DMPC, the viscosity has been determined to be about 1.5 P, a value about 200 times greater than that of water and equivalent (approximately) to that of a light oil.26 However, from the center of the bilayer to the surface, 13C NMR has been used to demonstrate a 100-200-fold gradient of disorder (expressed as microviscosity).22 The hydrocarbon chains near the headgroups are much more crystalline, therefore, than in the center of the bilayer. The liposomal interfacial transfer process initially involves, as a result, solute "extraction" from an organic environment that is much more structured than a simple liquid. This situation may be reasonably expected to result in a significant slowing of the phase transfer process.At the headgroup region of a liposome, a very complex structure exists. The phosphatidylcholine headgroup binds water tightly: calorimetric experiments, for example, indicate that 10 mol of water per mole of synthetic lecithin is unfreezable at 0 °C;23 using (25) Guy, R.

The far-infrared spectra of neutral and cationic niobium clusters: Nb5∕+ to Nb9∕+

“…13,[26][27][28][29][30][31][32][33][34][35] The reaction rate towards H 2 and N 2 is found to correlate with the electronic properties as expressed, e.g., by an ͑effective͒ ionization potential of the cluster. 13,34 The presence of isomers for several cationic and neutral clusters in the size range between 9-20 atoms has been observed in reactivity studies [30][31][32][33][34][35] but also spectroscopically. 12,14,15 In electric deflection experiments on neutral niobium clusters a strong variation in the per-atom polarizability has been found and it has been suggested that this is related to large size-dependent variations in the electronic or geometric structures.…”

Broken-symmetry unrestricted hybrid density functional calculations on nickel dimer and nickel hydride

“…[3][4][5] The rapid development of experimental techniques in recent years has made it possible both to obtain size-controlled transition metal clusters and to study their reactivity against chemisorption processes. [6][7][8][9] Methods for studying properties and behavior of clusters have been developed, and a review on computational studies of clusters has been written by Freeman and Doll. 10 There have been many studies on nickel clusters using various methods of exploring the potential energy surfaces ͑PES͒.…”

Reaction of tungsten anion clusters with molecular and atomic nitrogen

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] For example, oxygen adsorption reactivities of Au anion clusters exhibit an even/odd alternation, i.e., Au anion clusters with even numbered gold atoms are active for oxygen adsorption, whereas odd-numbered clusters are inert. 5 Rates of chemisorption for H 2 , D 2 , and N 2 on Fe n ͑Refs.…”

“…5 Rates of chemisorption for H 2 , D 2 , and N 2 on Fe n ͑Refs. 8 and 9͒ and Nb n clusters, [10][11][12][13][14] and CO on different metal clusters 15 vary by several orders of magnitudes as a function of n. Tungsten clusters (W n , nϭnumber of atoms͒ with nϽ15 show relatively low reactivities toward nitrogen adsorption, whereas a sharp jump of the reactivity is detected for n ϭ15 at liquid-nitrogen temperature as well as room temperature. 6,7 In many cases, correlations between electronic structures ͑for example, ionization potentials͒ and chemisorption reactivities of metal clusters have been found.…”