A Theoretical Study on the Relationship between Nucleophilicity and Ionization Potentials in Solution Phase

Abstract

In this paper we describe a method to obtain estimates of the relative nucleophilicity for a series of neutral and charged electron donors from their solution phase ionization potential (I s ). The relationship between nucleophilicity and the solution phase ionization potentials is first tested for experimental I s values in aqueous solution. On the basis of the meaningful relationship found, the method is then applied to the theoretical solution phase I s obtained at the IPCM-MP2/6-311G(2d,p) level of theory. The comparison between the experimental nucleophilicity as given by Ritchie's N+ scale and the solution phase ionization energy for a series electron donors split out into two families: a first group of marginal and moderate nucleophiles that mainly contains atoms of the first row (H 2 O, NH 2 CONHNH 2 , CF 3 CH 2 NH 2 , NH 3 , CH 3 ONH 2 , NH 2 OH and CH 3 O -), with nucleophilicity number N+ < 6.0; a second group of strong nucleophiles, mainly including second-row sulfur atom (CH 3 CH 2 S -, CH 3 CH 2 CH 2 S -, OHCH 2 CH 2 S -, C 6 H 5 S -) and the first-row electron donors piperidine and morpholine, with nucleophilicity number N+ > 7.0. An approximate expression for a local nucleophilicity index is proposed. The results show that the nucleophilicity power of the electron donors is consistently shown at the expected nucleophilic sites in these molecules. The solvent effect on the predicted nucleophilicity is also discussed.

Solvatochromism and Molecular Selectivity of C-(4-chlorophenyl)-N-phenylnitrone: A Photophysical Study

“…A linear correlation with the E T (30) scale of solvent polarity is indicative of Figure 3 indicated that the transition is accompanied by a decrease in the dipole moment for the nitrone N1, as is also true for the indicator dye of the E T (30) scale. The poorer sensitivity of E(F) compared to E(A) towards change in the solvent polarity was observed.…”

“…The present paper reports the trend of forming charge transfer complexes by the nitrone (N1) with the unsaturated ketones (K1 -K3) in terms of experimental transition dipole strengths, resonance energies and formation constants of the complexes in non-polar toluene medium. Experimental findings of the trend in non-covalent interaction were well substantiated theoretically with the help of DFT calculated electrophilicity and nucleophilicity indices [23,24,[28][29][30] as well as in terms of frontier molecular orbital energies [24].…”

Global and Local Reactivity Descriptors Based on Quadratic and Linear Energy Models for α,β-Unsaturated Organic Compounds

“…To describe the nucleophilicity N F D of a molecule we adopted the method proposed by Contreras et al [18], where …”

“…This is the main objective of the so-called conceptual DFT [2,3,4,5,6,7,8,9,10], which gives rise to global and local indicators or descriptors. Among the global indicators one distinguishes the chemical potential [11], chemical hardness [12,13,14], electrophilicity [15,16,17] and nucleophilicity [18,19]. On the other hand local descriptors as the fukui function [20,21,22] f (r ) are able to distinguish the most reactive region in a molecule.…”

A DFT Study of the Reactivity Indexes of Ionic [4 + 2+] Diels-Alder Cycloaddition to Nitrilium and Immonium Ions

“…In a formal framework it has allowed introducing in a many empirical chemical concepts like electronegativity [10], hardness [11], so-called reaction force [12], Fukui function [13], electrophilicity [14], electrofugality and nucleofugality [1,2,9,[15][16][17][18], nucleophilicity and solution phase ionization potentials, homofugality [19,20], nucleophilicity [21], among others. In particular, the introduction of concepts like electrophilicity and nucleophilicity to define electron deficient (electrophile) and electron rich (nucleophile) species has gained a continuous interest to construct empirical scales classifying atoms, molecules and charged species [22][23][24][25][26][27][28][29].…”