Electrostatics for probing lone pairs and their interactions

Abstract

The value of the molecular electrostatic potential minimum (V ) and its topographical features (position, as well as the eigenvalues and eigenvectors of the corresponding Hessian matrix) are recently proposed as the criteria for characterizing a lone pair (Kumar A. et al., J. Phys. Chem. 2014, A118, 526). This electrostatic characterization of lone pairs is examined for a large number of small molecules employing MP4/6-311++G(d,p)//MP2/6-311++G(d,p) theory. The eigenvector of the Hessian matrix corresponding to its largest eigenvalue (λ ), is found to be directed toward the lone pair-bearing-atom, with λ showing a strong linear correlation with V . Large magnitudes of V and λ indicate a charge-dense lone pair. The topographical features of V are seen to provide insights into the interactive behavior of the molecules with model electrophiles, viz. HF, CO , and Li . In all the complexes of HF and majority of the other complexes, the interaction energy (E ) correlates well with the respective V value, but for some deviations occurring due to other competing secondary interactions. The electrostatic interactions are found to be highly directional in nature as the orientation of interacting atom correlates strongly to the position of lone pair. In summary, the present study on a large number of test molecules shows that electrostatics is able to probe lone pairs in molecules and offers a simple interpretation of chemical reactivity. © 2017 Wiley Periodicals, Inc.

Mechanism and Stereoselectivity of the Elementometalation Process of Activated Alkyne RCCR(RCO2Me) by Cp2TaH3

“…The electrostatic interactions are found to be highly directional in nature as the orientation of interacting atom correlates strongly to the position of lone pair . The MEP is able to probe lone pairs in molecules and offers a simple interpretation of chemical reactivity …”

“…[62] The MEP is able to probe lone pairs in molecules and offers a simple interpretation of chemical reactivity. [63] To investigate the interaction sites in the adduct, the MEP of Cp 2 TaH 3 and RC CR were obtained. Their MEP graphs on the 0.001 a.u.…”

Lone pairs mapping by Laplacian of 3He NMR chemical shift

“…[8,9] The magnitude of MESP minima correlates well with the degree of LP localization. [10][11][12] The electron localization function (ELF) is widely used for mapping of outer electronic shells. [13][14][15][16][17] For example, local maxima of ELF indicate "localization attractors" (bonding, nonbonding, and core).…”

Prelude to molecular dynamics: Topography‐driven gaussian charge models

“…Rank of a nondegenerate CP of MESP scalar field is 3 and possible four types of CPs are: (3, +3), (3, −3) which represent local minimum, local maximum and (3, +1), (3, −1) are different types of saddles. These nondegenerate CPs bring out chemically significant features: a (3, +3) CP signifies presence of lone pairs or π bonds in molecules . Each bonded pair of atoms is reflected by presence of (3, −1) saddle.…”

“…These nondegenerate CPs bring out chemically significant features: a (3, +3) CP signifies presence of lone pairs or π bonds in molecules. [12][13][14][15] Each bonded pair of atoms is reflected by presence of (3, −1) saddle. A (3, +1) CP is found to connect two minima and indicate presence of a ring or cage in the nuclear framework.…”