Valence‐bond studies of four‐electron three‐center bonding units. II. FNO, HNO, LiNO, LiON, and HF₂⁻

Abstract

AbstractsFor each of HNO, FNO, LiNO, LiON and HFZ-, ab initio valence-bond wave functions are reported for the four-electron three-center bonding unit which involves one of the following sets of atomic orbitals: (a) NXg-bond ( X = H, For Li) and oxygen 2pn'; (b) LiO u-bond and nitrogen 2~7~' ; (c) hydrogen 1s and fluorine 2pu. Six S = 0 valence-bond structures pertain for this type of bonding unit. For HFZ-and FNO, the calculated bond-eigenfunction coefficients for some of these valencebond structures differ appreciably according to whether the Slater determinants include only the electrons of the four-electron three-center bonding unit, or all of the valence-shell + inner-shell electrons. For HNO, LiNO, and LiON, the all-electron and all valence-shell electron calculations generate similar sets of bond-eigenfunction coefficients. For each of the nitrosyl systems, the bond-eigenfunction coefficient with largest magnitude is calculated to be that for which zero atomic formal charges occur in the valence-bond structure. Qualitative valence-bond and "increasedvalence" descriptions of the bonding are presented.

A Valence Bond Study of Three-Center Four-Electron π Bonding: Electronegativity vs Electroneutrality

“…In the present paper, we seek to elucidate the bonding in three-center four-electron π units such as ozone through VB methods. Although the σ system is more complicated than the localized homopolar bonding picture in Figure , ,, we have chosen to focus solely on π bonding herein. Valence bond theory is ideally suited for this type of problem due to its ability to break apart the wave function into contributing segments.…”

Nitrogen–fluorine compounds

“…IX. The one-electron delocalisation indicated in the Kekulé-type Lewis structures X also generates IX, which is equivalent to the X $ XI resonance [25,34,35,58,59]. for NH 2 F, NF 3 and NF4+.…”

Parametrized Valence Bond Studies of the Origin of the N−F Bond Lengthenings of FNO2 and FNO

“…Ionic F - NO 2 + increased-valence structures, which participate in resonance with the covalent increased-valence structures of VI and VIII , are displayed in ref a. Increased-valence structures have been derived for FNO in refs a, , and 25 (cf. Figure here also) and for F 3 NO in refs a, , and 27.…”