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2. Comments on the electrostatic minimum potential (V (sub)min) as a measure of the electron-donating power of PZ (sub)3

Author

Giering, Warren P., Prock, Alfred, and Fernandez, Anthony L.

Subjects
Chemistry, Inorganic -- Research, Electrons -- Properties, Electrostatics -- Properties, Inorganic compounds -- Chemical properties, Inorganic compounds -- Composition, Ligands -- Composition, Ligands -- Properties, Molecules -- Chemical properties, Phosphorus compounds -- Chemical properties, Substitution reactions -- Analysis, Chemistry
Abstract

The authors discuss electrostatic minimum potential (V (sub)min). The hypothesis that this potential could be used as a quantitative measure of the sigma donating power of substituted phosphorus(III) ligands has been tested, and the results are reported.

Published
2003

3. Time resolved surface and volume generated photocurrent in a fluid aromatic solution.

Author

Prock, Alfred

Subjects
*FLUIDS, *ELECTRONIC excitation
Abstract

Time resolved photocurrent following a pulse was measured for the system tetraphenylporphyrin solution in fluorobenzene contained between tin oxide semiconductor electrodes. Analysis is presented in terms of surface and volume generation of photocurrent. The one-dimensional diffusion equation for triplet state excitation diffusion to the electrode is modified to include a nonlinear term for bimolecular excitation self-quenching. Numerical computation for selected parameters provides a good fit for both amplitude and shape of photocurrent transients over a range of a factor of 480 in initial excitation density. Both excitation lifetime and the quenching rate constant are evaluated. Results are consistent with the model for extrinsic photocurrent generation based on the precursor being bulk triplet state excitation in such aromatic systems. Additionally, computation demonstrates that the quantum efficiency of extrinsic photocurrent production remains high when electrode separation is comparable with excitation diffusion length, falling by only 30% when the pseudo-first order quenching rate constant is as large as ten times the inverse triplet lifetime. [ABSTRACT FROM AUTHOR]

Published
1985
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9. Terpsichorean movements of pentaammineruthenium on pyrimidine and isocytosine ligands

Author

LaChance-Galang, Kathleen J., Maldonado, Ishael, Gallagher, Louise M., Clarke, Michael J., Jian, Wei, Galang, Roy D., Prock, Alfred, and Chacklos, Jerome

Subjects
Cytosine -- Research, Cytosine -- Chemical properties, Pyrimidines -- Research, Pyrimidines -- Chemical properties, Ruthenium -- Research, Ruthenium -- Chemical properties, Isomerization -- Research, Chemistry
Abstract

Pentaammineruthenium moves on ambidentate nitrogen heterocycles by both rotation and linkage isomerization. These movements can be choreographed by pH and electrochemical potential.

Published
2001

36. Comments on the Electrostatic Minimum Potential (V[sub min]) as a Measure of the Electron-Donating Power of PZ[sub 3].

Author

Giering, Warren P., Prock, Alfred, and Fernandez, Anthony L.

Subjects
*PHOSPHORUS, *LIGANDS (Chemistry), *ELECTROSTATICS
Abstract

Focuses on the electrostatic minimum potential as a measure of the electron-donating power of phosphorus ligands. Correlations between a number of physicochemical properties and electrostatic minimum potential; Quantitative analysis of ligand effects; Lack of involvement of stereoelectronic effects.

Published
2003
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37. Analysis of the enantioselectivities and initial rates of the hydrosilylation of acetophenone catalyzed by [Rh(cod)Cl]2/(chiral diphosphine). The quantitative analysis of ligand effects

Author

Reyes, Clementina, Prock, Alfred, and Giering, Warren P.

Subjects
*CATALYSIS, *LIGANDS (Chemistry)
Abstract

Through the application of the quantitative analysis of ligand effects (QALE) method to the study of the hydrosilylation of acetophenone, we have shown, for the first time, that the initial rate and enantioselectivity of a complicated catalytic system responds in a rational manner to the variations in the stereoelectronic properties of the silane. The reactions (in benzene-d6 at 63 °C) were catalyzed by [Rh(cod)Cl]2/(chiral diphosphine) (chiral diphosphine=(R)-BINAP [(R)-(+)-2,2′-bis(diphenylphosphino)-1,1′binaphthyl], (R,R)-tolyl-BINAP [(R)-(+)-2,2′-bis(di-p-tolylphosphino)-1,1′-binaphthyl], (R,R)-Me-DUPHOS [(R,R)-(–)-1,2-Bis-2,5-dimethylphospholano)benzene], (R,R)-DIOP [(R,R)-(−)-2,3-O-isopropylidine-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane], and (R)-QUINAP [(R)-(+)-1-(2-diphenylphosphino-1-naphthyl)isoquinoline]. The ee''s (R) of the hydrosilylation products (CH3CH(OSiR3)Ph) range between −9 and 53% with the (R)-QUINAP giving the poorest enantioselectivity. The QALE analyses of log(R/S) for (R)-BINAP, (R)-tolyl-BINAP, (R,R)-Me-DUPHOS, and (R,R)-DIOP reveal that the steric effects associated with the silanes are not monotonic. [Copyright &y& Elsevier]

Published
2003
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