Identification of a Simplest Hypervalent Hydrogen Fluoride Anion in Solid Argon

Abstract

Hypervalent molecules are one of the exceptions to the octet rule. Bonding in most hypervalent molecules is well rationalized by the Rundle–Pimentel model (three-center four-electron bond), and high ionic bonding between the ligands and the central atom is essential for stabilizing hypervalent molecules. Here, we produced one of the simplest hypervalent anions, HF−, which is known to deviate from the Rundle–Pimentel model, and identified its ro-vibrational features. High-level ab inito calculations reveal that its bond dissociation energy is comparable to that of dihalides, as supported by secondary photolysis experiments with irradiation at various wavelengths. The charge distribution analysis suggested that the F atom of HF− is negative and hypervalent and the bonding is more covalent than ionic.

Direct infrared observation of hydrogen chloride anions in solid argon

“…It is worth noting that in our previous work, irradiation of the electron-bombarded matrix sample (CH 3 F/Ar) at 210 nm enhanced the formation of HF efficiently. 17 However, in the present study, the amount of HCl increased somewhat upon irradiation of the matrix sample (CH 3 Cl/Ar) at 450 nm, as shown in Fig. 3(D).…”

“…The experimental setup has been described previously. 17,21,22 IR absorption spectra covering the spectral range of 450-5000 cm 1 were recorded with an interferometric spectrometer (Bruker v80) equipped with a KBr beam splitter and a Hg-Cd-Te detector cooled to 77 K. Typically, 400 scans at a resolution of 0.25 cm 1 were recorded at each stage of the experiment. The anions were produced by electron bombardment of a gaseous sample containing a small proportion of CH 3 Cl during the deposition of an Ar matrix.…”

“…In our previous work, 17 we produced and trapped hydrogen fluoride anions (HF ) in a solid Ar matrix; these anions were generated by electron bombardment of an Ar matrix containing a small amount of CH 3 F during deposition and were identified by observing the ro-vibrational bands of the HF stretching mode. The calculated valence electron equivalent (γ), which describes the effective number of valence electrons on any particular atom based on an analysis of the atomic charges in the molecule, 18 indicated that the F atom of this anion is hypervalent.…”

Infrared Spectra of the 1-Methylvinoxide Radical and Anion Isolated in Solid Argon

“…The experimental setup has been described previously. − IR absorption spectra covering the spectral range of 400–5000 cm –1 were recorded on a Fourier-transform IR spectrometer (v80, Bruker) equipped with a KBr beam splitter and Hg–Cd–Te detector cooled to 77 K. Typically, 400 scans at a resolution of 0.25 cm –1 were recorded at each stage of an experiment.…”