Valence Bond Studies of N2F+

Abstract

The results of STO-6G valence bond (VB) calculations for the linear cation N 2 F + show that (a) the dominant Lewis-type VB structures involve a single positive charge which is located on either of the nitrogen atoms, and (b) a small amount of N-F π-bonding arises primarily from the formation of one-electron N-F π-bonds. It is suggested that N-F π-bonding is one of several factors which are responsible for the shortening of the N-F bond of N 2 F + relative to that of NF + 4 . Valence bond and bond length considerations imply that the extent of N-O π-bonding in N 2 O and NO 3− 4 exceeds the degree of N-F π-bonding in N 2 F + and NF + 4 .

Fluoro‐nitrogen Cations

“…In sp 2 hybridised [N 2 F 3 ] + , the unique N−F bond is slightly longer than those of the NF 2 group, because the nitrogen with the unique fluorine has an electron density feeding free valence electron pair, thus decreasing its effective electronegativity. Although the short N−F bond in N 2 F + might be explained by valence bond theory assuming a minor contribution from N−F π‐bonding, [37] this interpretation is not very plausible because the corresponding resonance structure results in a positive charge on fluorine and repulsive neighbouring positive charges on N [Eq. 5].…”

Theoretical Study of Complexes and Fluoride Cation Transfer between N2F+and Electron Donors

“…It has been used as a precursor of N 5 + salts and as an electrophilic fluorinating agent . The theoretical studies of this cation have been limited to the characterization of its bonding. − …”

Nitrogen–fluorine compounds

“…(47)) in structure C that has the shortest known N-F bond (d (N-F) 122 pm, d(N-N) 109.9 pm). N 2 F + is isoelectronic with NO 2 + [63,64].…”

“…In VB terms the negative hyperconjugation discussed above for the cis isomer (A) of FNNF can be accounted for by a double-(triple-)bond-no-bond resonance between FNNF and F À and N 2 F + (see below) [63].…”