Roots of Acetate-Vanadium Linkage Isomerism: A QTAIM Study

Abstract

The possibility of linkage isomerism in a number of vanadium(IV) and vanadium(V) complexes with acetate was surveyed using Density Functional Theory (DFT) and Bader's Quantum Theory of Atoms in Molecules (QTAIM). The results show that vanadium-acetate linkages may be classified as bidentate symmetrical, bidentate asymmetrical, or monodentate, the latter being observed in about 40% of the cases. These latter ones correspond to situations where the two oxygen atoms of the acetate moiety are not equivalent. They are associated with an energy penalty of about 263 kJ·mol(-1), as determined by the distribution of the scaled kinetic energy of the atomic basins forming the acetate ligand. In the presence of bidentate symmetrical vanadium-acetate linkages, the inner valence-shell charge concentrations on the vanadium atom deviate from the traditional VSEPR-derived arrangement, with an energy penalty of about 780 kJ·mol(-1). A compromise situation is partially accomplished in the case of bidentate asymmetrical linkages, which allow a Gillespiean-like arrangement of the inner valence-shell charge concentrations. In this case, one of these local charge concentrations lies close to a V-OAcO bond, which slightly disrupts the equivalence between the two oxygen atoms in the acetate ligand.

Exploring rare chemical phenomena using fractional nuclear charges: Thecis‐effect in N2F2

“…The results from both Natural and QTAIM population analysis are in excellent accordance, as expected from previous comparative studies . The QTAIM atomic populations ( ) of N (1) , N (2) , F (3) , and F (4) reflect the expected effect of tinkering with the nuclear charges of each system: atoms for which the nuclear charge was greater than the one found in nature are more electronegative and capable of withdrawing more electron density from their neighbors.…”

TMtopo Dataset — Quantum Geometries and Density Topology for 1.1k Transition Metal Complexes

“…The relatively large dispersion of E Mol /n electrons shown in Figure 5a is justifiable by the relatively small impact the iVSCC should have on the potential felt by the electrons in the atomic basins pertaining to the ligands of each TM complex. Although relying on a local adherence to the virial theorem, the negative value of the electronic kinetic energy in the metal basin, −K(M), is a suitable surrogate for contribution of the metal's population to the electronic energy of the molecule, specially when considering general trends in the data 30,40 .…”

“…These observations had lead to the conclusion that the penultimate shell (usually referred to as the inner-Valence Shell, iVS) of the metal center of a TM complex is not isotropic and that the molecular geometry in these complexes is dictated by the lowering of the repulsion among these iVS Charge Concentrations (iVSCC) that lie opposite to each ligand. [26][27][28] More recently, a detailed analysis of several vanadium-acetate complexes under the more framework of the Quantum Theory of Atoms in Molecules (QTAIM) has revealed some important exceptions of Gillespie's observations 30 . Although vanadium-acetate complexes in which acetate behaved as a mono-dentate ligand usually conformed to Gillespie's observations, the ones with at least one bidentate acetate ligand did not.…”

“…Although vanadium-acetate complexes in which acetate behaved as a mono-dentate ligand usually conformed to Gillespie's observations, the ones with at least one bidentate acetate ligand did not. What is more, when partitioning the molecular energy by the individual atomic basins under the QTAIM framework, the former complexes show a lower energy for the metal center, whereas the latter show a stabilization of the atoms in the acetate moiety, due to the electron delocalization along the V−O−C−O ring 30 . These results lead to the hypothesis that QTAIM properties derived from the analysis of both the electron density, ρ(r), as well as ∇ 2 ρ(r) could be useful for creating novel ML models predicting molecular geometries, as well as other important aspects of TM-complexes.…”

Structural, Spectroscopic, and Chemical Bonding Analysis of Zn(II) Complex [Zn(sal)](H2O): Combined Experimental and Theoretical (NBO, QTAIM, and ELF) Investigation

“…Furthermore, we also employed NBO methodology to elucidate whether the Zn ( Figure 5). The values of the second order stabilization energy ∆E (2) and also the difference between (Zn2) and 3d z 2 (Zn2) → σ* (Zn1) were stabilized by ∆E (2) of 0.93 and 0.96 kcal mol −1 , respectively them were very small, which ruled out the existence of metallophilic interactions between the zinc atoms [87][88][89]. Hence, the small values of ∆E (2) indicated that the Zn•••Zn interaction was attractive and dispersive in nature.…”