Electron localization function and electron localizability indicator applied to study the bonding in the peroxynitrous acid HOONO

Abstract

The ground-state electronic structure of peroxynitrous acid (HOONO) and its singlet biradicaloid form (HO···ONO) have been studied using topological analysis of the electron localization function (ELF), together with the electron localizability indicator (ELI-D), at the DFT (B3LYP, M05, M052X, and M06), CCSD, and CASSCF levels. Three isomers of HOONO (cis-cis, cis-perp, and trans-perp) have been considered. The results show that from all functionals applied, only B3LYP yields the correct geometrical structure. The ELF and ELI-D-topology of the O-O and central N-O bonds strongly depends on the wave function used for analysis. Calculations carried out at CAS (14,12)/aug-cc-pVTZ//CCSD(T)/aug-cc-pVTZ level reveal two bonds of the charge-shift type: a protocovalent NO bond with a basin population of 0.82-1.08e, and a more electron depleted O-O bond with a population of 0.66-0.71e. The most favorable dissociation channel (HOONO → HO + ONO) corresponds to breaking of the most electron-deficient bond (OO). In the case of cis- and trans-HO···ONO, the ELF, ELI-D, and electron density fields results demonstrate a closed-shell O···O interaction. The α-spin electrons are found mainly (0.64e) in the lone pairs of oxygen V(i) (= 1,2)(O) from the OH group. The β-spin electrons are delocalized over the ONO group, with the largest concentration (0.34e) on the lone pair of nitrogen V(N).

Peroxynitrous acid: controversy and consensus surrounding an enigmatic oxidant

“…28 Deuterium kinetic isotope effect results 58 tend to support a mechanism involving the (N-O)-O bending movement. We note that the geometries of ONOOH in the trans-perp state 115 and in the triplet state 28 are quite different, which is not surprising, as the energy of the triplet state lies roughly 45 kJ mol −1 28 above that of the trans-perp state. 115 Recently, a "roaming" mechanism, which proceeds without a transition state, has been invoked to describe formation of O 2 and NO˙from NO 3˙i n the gas phase; 116 if a roaming mechanism applies to isomerisation of ONOOH, it may be envisioned that HO˙does not completely dissociate and roams about NO 2˙u ntil HNO 3 is formed.…”

A Variety of Bond Analysis Methods, One Answer? An Investigation of the Element−Oxygen Bond of Hydroxides HnXOH

“…[11,35] We only regard the ELI-D and not the electron localization function (ELF), which largely behaves in the same way unless highly correlated calculations are carriedo ut. [36] As opposed to the basinso f the electron density,t here are different types of ELI-D basins: There are core basins as wellasvalence basins whose synapticities are characterizedb yt he number of core basins they are in contact with. [37] Monosynaptic valence basins are in contact with one core basin and can be attributed to lone pairs, whereas disynaptic valence basins, which may be associated to bonds, are in contact with two core basins.…”

“…The electron localizability indicator (ELI‐D), which is calculated from properties of the molecular wavefunction, is a scalar field that describes the distribution of electrons: Electrons are localized in regions of large ELI‐D values . We only regard the ELI‐D and not the electron localization function (ELF), which largely behaves in the same way unless highly correlated calculations are carried out . As opposed to the basins of the electron density, there are different types of ELI‐D basins: There are core basins as well as valence basins whose synapticities are characterized by the number of core basins they are in contact with .…”

Lone pairs mapping by Laplacian of 3He NMR chemical shift

“…The magnitude of MESP minima correlates well with the degree of LP localization . The electron localization function (ELF) is widely used for mapping of outer electronic shells . For example, local maxima of ELF indicate “localization attractors” (bonding, nonbonding, and core).…”

“…[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). In addition, MESP and ELF can be mathematically retrieved from experimentally measured electron density.…”