Substituent effects on chemical reactivity. Improved evaluation of field and resonance components

1983 ◽  
Vol 105 (3) ◽  
pp. 492-502 ◽  
Author(s):  
C. Gardner Swain ◽  
Stefan H. Unger ◽  
Niles R. Rosenquist ◽  
Marguerite S. Swain
Keyword(s):  
Chemical Reactivity ◽  
Substituent Effects

Computational study of substituent effects on the acidity, toxicity and chemical reactivity of bacteriostatic sulfonamides

2018 ◽  
Vol 81 ◽  
pp. 116-124 ◽  
Author(s):  
Catalina Soriano-Correa ◽  
Carolina Barrientos-Salcedo ◽  
Misaela Francisco-Márquez ◽  
C. Ignacio Sainz-Díaz
Keyword(s):  
Computational Study ◽  
Chemical Reactivity ◽  
Substituent Effects

scholarly journals Consistent Inclusion of Continuum Solvation in Energy Decomposition Analysis: Theory and Application to Molecular CO2 Reduction Catalysts

2020 ◽  
Author(s):  
Yuezhi Mao ◽  
Matthias Loipersberger ◽  
Kareesa Kron ◽  
Jeffrey Derrick ◽  
Christopher Chang ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Chemical Reactivity ◽  
Decomposition Analysis ◽  
Substituent Effects ◽  
Co2 Reduction ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Coulombic Interaction ◽  
Model Complexes ◽  
Localized Molecular Orbitals

<p>To facilitate computational investigation of intermolecular interactions in the solution phase, we report the development of ALMO-EDA(solv), a scheme that allows the application of continuum solvent models within the framework of energy decomposition analysis (EDA) based on absolutely localized molecular orbitals (ALMOs). In this scheme, all the quantum mechanical states involved in the variational EDA procedure are computed with the presence of solvent environment so that solvation effects are incorporated in the evaluation of all its energy components. After validation on several model complexes, we employ ALMO-EDA(solv) to investigate substituent effects on two classes of complexes that are related to electrochemical CO<sub>2</sub> reduction catalysis. For [FeTPP(CO<sub>2</sub>−κC)]<sup>2−</sup> (TPP = tetraphenylporphyrin), we reveal that two ortho substituents which yield most favorable CO2 binding, −N(CH<sub>3</sub>)<sub>3</sub><sup>+</sup> (TMA) and −OH, stabilize the complex via through-structure and through-space mechanisms, respectively. The Coulombic interaction between the positively charged TMA group and activated CO<sub>2</sub> is found to be largely attenuated by the polar solvent. Furthermore, we also provide computational support for the design strategy of utilizing bulky, flexible ligands to stabilize activated CO<sub>2</sub> via long-range Coulomb interactions, which creates biomimetic solvent-inaccessible “pockets” in that electrostatics is unscreened. For the reactant and product complexes associated with the electron transfer from the <i>p</i>-terphenyl radical anion to CO<sub>2</sub> , we demonstrate that the double terminal substitution of <i>p</i>-terphenyl by electron-withdrawing groups considerably strengthens the binding in the product state while moderately weakens that in the reactant state, which are both dominated by the substituent tuning of the electrostatics component. These applications illustrate that this new extension of ALMO-EDA provides a valuable means to unravel the nature of intermolecular interactions and quantify their impacts on chemical reactivity in solution.<br></p>

Substituent effects on the stability, physicochemical properties and chemical reactivity of nitroimidazole derivatives with potential antiparasitic effect: a computational study

2019 ◽  
Vol 43 (28) ◽  
pp. 11125-11134 ◽  
Author(s):  
Linda Campos-Fernández ◽  
Carolina Barrientos-Salcedo ◽  
Edtson E. Herrera Valencia ◽  
Rocío Ortiz-Muñiz ◽  
Catalina Soriano-Correa
Keyword(s):  
Drug Discovery ◽  
Physicochemical Properties ◽  
Neglected Tropical Diseases ◽  
Computational Study ◽  
Chemical Reactivity ◽  
Substituent Effects ◽  
Research Interest ◽  
Tropical Diseases ◽  
The Stability ◽  
Parasitic Pathogens

Neglected tropical diseases caused by parasitic pathogens have caused an increase in research interest in drug discovery.

Characterization of Tris(Diselenocarbamato)Cobalt(III) and Pentakis(Diselenocarbamato)Dicobalt(III) Complexes by Electrochemical, Cobalt-59 N.M.R. and Mass-Spectrometric Techniques. Comparisons With Dithiocarbamate Analogs

1986 ◽  
Vol 39 (9) ◽  
pp. 1385 ◽  
Author(s):  
AM Bond ◽  
R Colton ◽  
DR Mann ◽  
JE Moir
Keyword(s):  
Electrochemical Oxidation ◽  
Chemical Shifts ◽  
Chemical Reactivity ◽  
Mercury Electrode ◽  
Substituent Effects ◽  
Reduction Process ◽  
Reduced Form ◽  
Platinum Electrodes ◽  
Redox Potentials ◽  
Mercury Electrodes

A series of Co(RR′dsc)3 and [Co2(RR′dsc)5]+ complexes (R, R′ = two alkyl groups or one heterocyclic group; dsc = NCSe2) have been synthesized and their redox behaviour, chemical reactivity and spectroscopic properties compared with the corresponding dithiocarbamate (RR′dtc) complexes. Electrochemical oxidation of Co(RR′dsc)3 in dichloromethane at platinum electrodes occurs at potentials about 0.34 V less positive than for Co(RR′dsc)3. The formally cobalt(IV) complexes [Co(RR′dsc)3]+ can be identified as a product which is then converted into [Co2(RR′dsc)5]+ via dimerization and an internal redox reaction. Despite the enhanced thermodynamic stability implied by the redox potentials, [Co(RR′dsc)3]+ has similar kinetic stability to the analogous dithiocarbamate complexes. Co(RR′dsc)3 is reduced at fairly negative potentials on both platinum and mercury electrodes with extremely rapid loss of [RR′dsc]-. [Co(RR′dsc)3]- is therefore thermodynamically and kinetically more unstable than [Co(RR′dtc)3]- . The [Co2(RR′dsc)5]+ complexes are also more readily oxidized and harder to reduce than the sulfur analogues. Oxidation of [Co2(RR′dsc)5]+ produces [Co2(RR′dsc)5]2+ at low temperatures and fast scan rates, but no stable reduced form of the dimer is accessible on the voltammetric time scale examined. The reduction process for the dimer is consistent with the reaction [Co2(RR′dsc)5]+ +e- → Co(RR′dsc)3+ Co(RR dsc)2. Electrochemical oxidation data obtained at mercury electrodes for the diselenocarbamate complexes are complicated by adsorption but are similar to that found at platinum electrodes. This contrasts with the dithiocarbamates where a mercury electrode specific pathway is observed. Cobalt-59 n.m.r. spectroscopy in dichloromethane shows the non- equivalence of the two cobalt atoms in [Co2(RR′dsc)5]+. The chemical shifts for Co(RR′dsc)3 complexes exhibit similar substituent effects to the dithiocarbamates in cobalt-59 n.m.r. measurements as was the case in oxidative electrochemistry. Cobalt-59 n.m.r. spectroscopy and mass spectrometry demonstrate that exchange, substitution and redox reactions can lead to the formation of mixed ligand diselenocarbamate complexes and mixed dithiocarbamate/diselenocarbamate complexes for both the cobalt(III) monomers and dimers.

exo-Substituent effects in halogenated icosahedral (B12H122–) and octahedral (B6H62–) closo-borane skeletons: chemical reactivity studied by experimental and quantum chemical methods

2009 ◽  
Vol 74 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Martin Lepšík ◽  
Martin Srnec ◽  
Drahomír Hnyk ◽  
Bohumír Grüner ◽  
Jaromír Plešek ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Chemical Shifts ◽  
Chemical Reactivity ◽  
Substituent Effects ◽  
Calculated Data ◽  
Reaction Pathways ◽  
Activation Barriers ◽  
Quantum Chemical Methods ◽  
B3lyp Method ◽  
Experimental Values

The exo-substituent effects in halogenated icosahedral B12H122– (B12) and octahedral B6H62– (B6) closo-borane skeletons were studied both experimentally and theoretically. Firstly, the equilibrium geometries of exo-substituted B12 and B6 clusters were obtained using quantum chemical calculations at the MP2/def2-SVP level. A comparison with the available X-ray crystallographic data revealed a very good agreement between the theoretical and experimental values. Secondly, other descriptors of the molecular structure of these borane compounds – 11B NMR chemical shifts – were experimentally determined and compared with the calculated values obtained by the ab initio/GIAO approach at the MP2/def2-TZVP level. It was shown that the calculated data reproduced the experiment very closely. Thirdly, we investigated experimentally the halogenation reactions of B12 and attempted to explain the observed ratios between the two obtained disubstituted products (meta/ortho ~ 4:1) by calculating their thermodynamic stabilities using the DFT/B3LYP method. These calculations showed the enhanced stability of the meta disubstituted B12 but did not explain why the para product had not been observed in the experiment. We thus turned our attention to the kinetic aspects of exo-substitution reactions by exploring the possible reaction pathways and transition states. In spite of the complexity of the plausible reaction mechanisms, reasonable agreement was obtained between the calculated activation barriers and the experimental observations concerning the halogenation reactions of the B6 and B12 molecules. It also allowed to exclude from considerations certain reaction pathways leading to the mono- and dihalogenated B12 and B6 species.

Empirical Energy−Density Relationships for the Analysis of Substituent Effects in Chemical Reactivity

2000 ◽  
Vol 122 (19) ◽  
pp. 4756-4762 ◽  
Author(s):  
P. Pérez ◽  
Y. Simón-Manso ◽  
A. Aizman ◽  
P. Fuentealba ◽  
R. Contreras
Keyword(s):  
Energy Density ◽  
Chemical Reactivity ◽  
Substituent Effects

scholarly journals Consistent Inclusion of Continuum Solvation in Energy Decomposition Analysis: Theory and Application to Molecular CO2 Reduction Catalysts

2020 ◽  
Author(s):  
Yuezhi Mao ◽  
Matthias Loipersberger ◽  
Kareesa Kron ◽  
Jeffrey Derrick ◽  
Christopher Chang ◽  
...  
Keyword(s):  
Intermolecular Interactions ◽  
Chemical Reactivity ◽  
Decomposition Analysis ◽  
Substituent Effects ◽  
Co2 Reduction ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Coulombic Interaction ◽  
Model Complexes ◽  
Localized Molecular Orbitals

<p>To facilitate computational investigation of intermolecular interactions in the solution phase, we report the development of ALMO-EDA(solv), a scheme that allows the application of continuum solvent models within the framework of energy decomposition analysis (EDA) based on absolutely localized molecular orbitals (ALMOs). In this scheme, all the quantum mechanical states involved in the variational EDA procedure are computed with the presence of solvent environment so that solvation effects are incorporated in the evaluation of all its energy components. After validation on several model complexes, we employ ALMO-EDA(solv) to investigate substituent effects on two classes of complexes that are related to electrochemical CO<sub>2</sub> reduction catalysis. For [FeTPP(CO<sub>2</sub>−κC)]<sup>2−</sup> (TPP = tetraphenylporphyrin), we reveal that two ortho substituents which yield most favorable CO2 binding, −N(CH<sub>3</sub>)<sub>3</sub><sup>+</sup> (TMA) and −OH, stabilize the complex via through-structure and through-space mechanisms, respectively. The Coulombic interaction between the positively charged TMA group and activated CO<sub>2</sub> is found to be largely attenuated by the polar solvent. Furthermore, we also provide computational support for the design strategy of utilizing bulky, flexible ligands to stabilize activated CO<sub>2</sub> via long-range Coulomb interactions, which creates biomimetic solvent-inaccessible “pockets” in that electrostatics is unscreened. For the reactant and product complexes associated with the electron transfer from the <i>p</i>-terphenyl radical anion to CO<sub>2</sub> , we demonstrate that the double terminal substitution of <i>p</i>-terphenyl by electron-withdrawing groups considerably strengthens the binding in the product state while moderately weakens that in the reactant state, which are both dominated by the substituent tuning of the electrostatics component. These applications illustrate that this new extension of ALMO-EDA provides a valuable means to unravel the nature of intermolecular interactions and quantify their impacts on chemical reactivity in solution.<br></p>

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