Electron donor strength

Compare energies fox meta andpara-nitroanilinium ions (intermediates in nitration of aniline). Are these differentiated to a lesser or greater extent than the intermediates in toluene nitration Examine electrostatic potential maps. What do these suggest about the relative electron-donor strengths of methyl and amino groups ... 

Iodine molecules adsorbed onto the structural aromatic rings provide information on the electron-donor strength, which appears to be higher in phenylene-bridged PMO than that reported for benzene and comparable with that reported for p-xilene. Traces of I3" species were also detected. From a comparison between two phenylene-bridged PMOs with different degree of order in the walls, aromatic rings in the material with amorphous walls appear more available for interaction with iodine. 

Lichtenberger DL, Johnston RL, Hinkelmann K, Suzuki T, Wudl F (1990) Relative electron donor strengths of tetrathiafulvene derivatives effects of chemical substitutions and the molecular environment from a combined photoelectron and electrochemical study. J Am Chem Soc 112 3302-3307... 

No physico-chemical methods exist that allow differences in one-electron donor strength for F centres, formed by alkali metal evaporation on the surfaces of various oxides, to be measured. However, there must be differences in one-electron donor ability because of their different catalytic activities. 

A systematic evaluation of the electron donor strengths of different amino groups by using NMR related with UV-Vis, IR and Raman, microwave and photoelectron spectral data, dipole moments, basicity, reactivity, electron and X-ray diffraction data and the results of quantum chemical calculations has been reviewed by Gawinecki and coworkers25. 

The film conductivity and the stability of TCNQ salt/polymer composites are strongly dependent on the matrix polymers, more specifically on the electron-donor strength of the p lymers which controls CT interaction with TCNQ salts. With Et,NH (TCNQ), ... 

Li, W. et al.. Field-effect transistors based on thiophene hexamer analogues with diminished electron donor strength, Chem. Mater. 11, 458 65, 1999. 

BD is crucial in activating the H-H bond toward homolytic cleavage to a dihydride. If BD becomes too strong, for example, by increasing electron-donor strength of co-ligands on M, the cr-bond cleaves to form a dihydride because of overpopulation of H2 fine line between H2 and dihydride coordination, and in some cases equilibria exist between the two forms in solution for W(CO)3(PR3)2(H2) (R = t -Pr A = 0.25) (Equation (3)). 

For the bicyclic amine DABCO stereoelectronic effects have been observed [59]. DABCO quenches DBO with lower rate constants than tertiary amines with similar electron donor strength, which can be explained by a hindered proton transfer in the initially formed exciplex. The resulting aminoalkyl radical is destabilized due to the unfavorable orientation of the amine lone pair and carbon radical center in a 60° angle. Noteworthy, the observed effects are much smaller than for alkoxyl radicals, which are known to react with amines exclusively via hydrogen atom transfer (see below). Similar observations have been reported for the quenching of triplet-excited benzophenone [29,195]. Also, stereoelectronic effects are deemed responsible for the three times lower quenching rate of DBO by diisopropylsulflde compared to dimethylsulflde. 

Interestingly, a change of the reactivity of singlet-excited DBO with sulfides upon going to the gas phase has been documented. In solution, amines quench DBO fluorescence faster than sulfides as expected, based on electron donor strength. This order of reactivity is inverted in the gas phase, where sulfides quench faster than amines [55,65]. 

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