Triazapentadienides, C(3)F(7)-C(=NR)-N=C(NHR)-C(3)F(7), result from the reaction of primary amines RNH(2) with the fluorinated imine C(3)F(7)-CF=N-C(4)F(9). The aniline derivative (R = Ph) is a weak monoprotic acid in dmso. Its conjugate base exhibits an extensive coordination chemistry. It acts as a bidentate ligand toward the molecular fragments Pd(C(3)H(5)), Rh(c-C(8)H(12)), Ir(c-C(8)H(12)), and Rh(CO)(2). The chelates [C(3)F(7)-C(NPh)-N-C(NPh)-C(3)F(7)](2)M, M = Mg, Mn, Fe, Co, Ni, Cu, Zn, and Pd, were prepared. In the crystallographically characterized Co complex, the metal is 3d(7), S = (3)/(2) and tetrahedrally coordinated. Spin densities at carbon in the C(6)H(5) and C(3)F(7) groups were estimated from the (1)H and (19)F contact shifts. Spin delocalization onto phenyl sp(2) carbons is approximately 10 times greater than onto the fluorinated sp(3) carbons.
A systematic study of gas-phase reactions of gold cations with alcohols is reported. These reactions are compared with the reactions of silver and copper cations with alcohols. In contrast with previous laser desorption/ionization studies, metal salts and/or metal oxides served as metal ion sources. Hydride abstraction is the dominant reaction of Au+ with alcohols.Study of methide and hydroxide abstraction reactions allows estimation of lower limits for Au-CH3, Cu-CH3, Au-OH, and Cu-OH bond dissociation energies (Z)(Au-CH3) > 27.1 kcal/mol, Z)(Cu-CH3) > 59 kcal/mol, D(Au-OH) > 62.5 kcal/mol, and Z)(Cu-OH) > 97.0 kcal/mol). Other primary reactions of Cu+ and Au+ include dehydration, with competitive elimination of H20 and the alkene via (¡-hydrogen transfer, and dehydrogenation, with elimination of H2, via -hydrogen transfer. Direct cationization is also observed. Silver cations mainly undergo cationization. The gas-phase acidity of AuH has been experimentally determined to be A//acid(AuH) = 331 ± 3 kcal/mol by using the bracketing technique.Gas phase metal ion chemistry studies have proliferated during recent years, particularly with the advent of laser desorption/ ionization (LD/I) methodologies introduced by Freiser and coworkers.1 To date, the majority have concentrated on the reactivity of Fe, Co, and Ni and variations in reactivity between
The n = 2 fine-structure transitions in positronium have been measured by observation of increased Lyman-a radiation at microwave induced resonances. We used an accelerator based slow positron beam to produce positronium in the 2 3 5'i excited state inside a waveguide. Our results are v 0 = 18499.65 ± 1.20±4.00 MHz, vi-13012.42±0.67±1.54 MHz, and v 2 =8 624.38 ±0.54 ± 1.40 MHz for the 2 3 S'i-* 2 3 Po,\,2 transition frequencies, respectively. The first error is statistical and the second is systematic. This is in agreement with recent bound state QED calculations.
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