On the Validity of the Maximum Hardness Principle and the Minimum Electrophilicity Principle during Chemical Reactions

2013 ◽  
Vol 117 (8) ◽  
pp. 1843-1852 ◽  
Author(s):  
Sudip Pan ◽  
Miquel Solà ◽  
Pratim K. Chattaraj
Keyword(s):  
Chemical Reactions ◽  
Maximum Hardness ◽  
Maximum Hardness Principle

scholarly journals An Assessment of the Validity of the Maximum Hardness Principle in Chemical Reactions

2017 ◽  
Vol 56 (3) ◽  
Author(s):  
Jordi Poater ◽  
Marcel Swart ◽  
Miquel Solà
Keyword(s):  
Transition State ◽  
Chemical Reactions ◽  
Maximum Hardness ◽  
Maximum Hardness Principle

We have computationally explored the fulfillment of the Maximum Hardness Principle in chemical reactions. To this end we have selected a well-defined series of 34 exothermic chemical reactions (the so-called BH76 test) and we have calculated the hardness of reactants, transition state, and products. Our results show that for only 18% of the reactions studied the hardness of the reactants is, at the same time, lower than that of the products and greater than that of the transition state, in agreement with the Maximum Hardness Principle. In most reactions we find that either the transition state has a higher hardness than the reactants or the reactants are harder that the products or both, and, therefore our results show that the Maximum Hardness Principle is disobeyed in most chemical reactions.

The generalized maximum hardness principle revisited and applied to atoms and molecules

2017 ◽  
Vol 19 (46) ◽  
pp. 30964-30983 ◽  
Author(s):  
Wojciech Grochala
Keyword(s):  
Gas Phase ◽  
Chemical Reactions ◽  
Maximum Hardness ◽  
Atoms And Molecules ◽  
Basic Concepts ◽  
Maximum Hardness Principle

Part 1 of this duology is devoted to isolated atoms and molecules, and to chemical reactions between them; we introduce here basic concepts beyond the Generalized Maximum Hardness Principle, and the corresponding Minimum Polarizability Principle, and we illustrate applicability of both principles to a broad range of chemical phenomena and distinct systems in the gas phase.

scholarly journals Favorable Direction in a Chemical Reaction Through the Maximum Hardness Principle

2017 ◽  
Vol 57 (1) ◽  
Author(s):  
Sudip Pan ◽  
Pratim K. Chattaraj
Keyword(s):  
Electronic Structure ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Transition States ◽  
Basis Sets ◽  
Maximum Hardness ◽  
Maximum Hardness Principle ◽  
Hardness Values

Recently, an assessment regarding the validity of maximum hardness principle has been done taking 34 exothermic chemical reactions (Poater, J.; Swart, M.; Solà, M. <em>J. Mex. Chem. Soc.</em> <strong>2012</strong>, <em>56</em>, 311) in which only 46% and 53% of the total reactions have greater hardness for the products and the reactants than those for the reactants and the transition states, respectively. They have also mentioned that a larger set of reactions should be studied to draw a general conclusion regarding the validity of maximum hardness principle. We have noticed that the reactions having fewer number of reactants than that of products and / or very hard atoms like H, N, O, F or very hard molecules like H<sub>2</sub>, N<sub>2</sub>, HF, HCN, CH<sub>4</sub>, etc. appearing in the reactant side, are more likely to disobey maximum hardness principle. In addition, dependence of hardness values on level of theory, basis sets, definitions, formulas, approximations should be kept in mind before criticising the validity of maximum hardness principle. Since these electronic structure principles are qualitative in nature, one should not expect them to be valid in all cases.

Electronegativity and redox reactions

2016 ◽  
Vol 18 (32) ◽  
pp. 22235-22243 ◽  
Author(s):  
Ramón Alain Miranda-Quintana ◽  
Marco Martínez González ◽  
Paul W. Ayers
Keyword(s):  
Redox Reactions ◽  
Oxidation Potential ◽  
Maximum Hardness ◽  
Maximum Hardness Principle

Using the maximum hardness principle, we show that the oxidation potential of a molecule increases as its electronegativity increases and also increases as its electronegativity in its oxidized state increases.

Tautomerism and the maximum hardness principle

2006 ◽  
Vol 106 (8) ◽  
pp. 1723-1735 ◽  
Author(s):  
Yi-Liang Zhang ◽  
Zhong-Zhi Yang
Keyword(s):  
Maximum Hardness ◽  
Maximum Hardness Principle

Synthesis, Structural Preference and Catalytic Activity of Neutral and Cationic Methylpalladium(II) Complexes Containing N-Arylpyridine-2-carbaldimine Chelating Ligands

2002 ◽  
Vol 67 (8) ◽  
pp. 1200-1214 ◽  
Author(s):  
Ana Arnaiz ◽  
Gabriel García-Herbosa ◽  
José V. Cuevas ◽  
Olivier Lavastre ◽  
Caroline Hillairet ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Chelating Ligands ◽  
Maximum Hardness ◽  
Neutral Complex ◽  
Synthesis And Crystal Structure ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Alkene Oligomerization ◽  
Maximum Hardness Principle ◽  
Rule Out

The syntheses and structures of neutral complexes [PdCl(Py-2-CH=NAr)(Me)] (Ar = 4-MeC6H4, 4-MeOC6H4, 4-CF3C6H4) and cationic complexes [Pd(Py-2-CH=NAr)(Me)(MeCN)]SbF6 (Ar = 4-MeC6H4, 4-MeOC6H4, 4-CF3C6H4) are described. The preference for the trans-isomers in the cationic complexes and for the cis-isomers in the neutral complexes is discussed on the basis of electronic arguments and supported by DFT calculations. The observed preference seems to follow the maximum hardness principle (MHP) introduced by Pearson. On the basis of the application of this principle to square planar complexes of palladium(II) and platinum(II) we propose the trans choice, which means that the hardest ligand arranges trans to the softest one. The synthesis and crystal structure of the related neutral complex trans-[Pd(CF3COO)(Py-2-CH=NC6H4-4-OMe)(Me)] is also described and allows to rule out the charge of the complex as the cause of isomeric preference. We also report our preliminary studies dealing with the catalytic activity of the cationic complexes in alkene oligomerization and copolymerization with CO.

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