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F De Proft

Publications and source records attributed to F De Proft.

5 recordsLinked to original sources
PubMed2003

Hirshfeld partitioning of the electron density: atomic dipoles and their relation with functional group properties.

Atomic dipole moments, derived within the Hirshfeld partitioning of the molecular electron density, have been studied for compounds of the type H-X and Cl-X, for a series of functional groups X frequently encountered in organic molecules. In the case of the H-X compounds, the component of the atomic dipole moment on H along the axis connecting H with the central atom in X is found to be linearly correlated with the electronegativity of X, the hardness of X playing no significant role. In the case of the Cl-X compounds, the situation is less clear. However, evidence seems to point to the conclusion that for these compounds, also the group hardness plays an important role.

Journal Article↗
PubMed2002

Atomic charges, dipole moments, and Fukui functions using the Hirshfeld partitioning of the electron density.

In the Hirshfeld partitioning of the electron density, the molecular electron density is decomposed in atomic contributions, proportional to the weight of the isolated atom density in the promolecule density, constructed by superimposing the isolated atom electron densities placed on the positions the atoms have in the molecule. A maximal conservation of the information of the isolated atoms in the atoms-in-molecules is thereby secured. Atomic charges, atomic dipole moments, and Fukui functions resulting from the Hirshfeld partitioning of the electron density are computed for a large series of molecules. In a representative set of organic and hypervalent molecules, they are compared with other commonly used population analysis methods. The expected bond polarities are recovered, but the charges are much smaller compared to other methods. Condensed Fukui functions for a large number of molecules, undergoing an electrophilic or a nucleophilic attack, are computed and compared with the HOMO and LUMO densities, integrated over the Hirshfeld atoms in molecules.

Journal Article↗
PubMed2001

Theoretical Study of [2 + 1] cycloaddition of CO and CS to acetylenes forming cyclopropenones and cyclopropenethiones.

The [2 + 1] cycloadditions of carbon monoxide and carbon monothioxide CX (X = O, S) to acetylenes (R1C triple bond CR2 with R1 = H, OH and R2 = CH3, OH, NH2, C6H5) have been studied at the B3LYP/6-311G(d,p) level. It has been shown that the reaction proceeds in two steps forming first an intermediate having the properties of both a carbene and a zwitterion followed by a ring closure leading to cyclopropenones or cyclopropenethiones. The solvent effect does not play an important role in the course of the cycloaddition. The estimation of the first vertical excitation energies by CIS and TD-B3LYP methods shows that the reactions likely take place in the ground state rather than in an excited state. All the studied cyclopropenones and cyclopropenethiones are aromatic as shown by their NICS values and confirmed by calculated and experimental NMR chemical shifts. Different reactivity criteria including HOMO coefficient, local softness, hardness, polarizability, and NICS are used to predict the site selectivity in all studied cases, and the NICS criterion seems to yield the best results among them.

Journal Article↗