Metal Oxo-Fluoride Molecules O_nMF₂ (M = Mn and Fe; n = 1–4) and O₂MnF: Matrix Infrared Spectra and Quantum Chemistry

Abstract

On reacting laser-ablated manganese or iron difluorides with O2 or O3 during codeposition in solid neon or argon, infrared absorptions of several new metal oxo-fluoride molecules, including OMF2, (η1-O2)­MF2, (η2-O3)­MF2, (η1-O2)2MF2 (M = Mn and Fe), and O2MnF, have been observed. Quantum chemical density functional and multiconfiguration wavefunction calculations have been applied to characterize these new products by their geometric and electronic structures, vibrations, charges, and bonding. The assignment of the main vibrational absorptions as dominant symmetric or antisymmetric M–F or M–O stretching modes is confirmed by oxygen isotopic shifts and quantum chemical calculations of frequencies and thermal stabilities. The tendency of Fe to form polyoxygen complexes in lower oxidation states than the preceding element Mn is affirmed experimentally and supported theoretically. The M–F stretching frequencies of the isolated metal oxo-fluorides may provide a scale for the local charge on the MF2 sites in active energy conversion systems. The study of these species provides insights for understanding the trend of oxidation state changes across the transition-metal series.

Electronic Structure and Spectroscopic Properties of Group-7 Tri-Oxo-Halides MO3X (M = Mn–Bh, X = F–Ts)

“…A 1−2% of the 3% discrepancy is due to the harmonic approximation. 65 For the heavier halogens from Br on, the calculated intensities of the metal−halogen stretching vibrations are predicted to be significantly weaker and cannot be easily measured. Remarkably, the wavenumbers of the vibrations of the (more covalent) MO units are calculated to be significantly larger, with scaling factors of 0.92(1) for the Tc and Re species but as low as 0.84(1) for the Mn species.…”

“…A few stretching vibrations of the dominant X–M character, v (2a 1 ), and of dominant symmetric and antisymmetric MO characters, v (1a 1 ) and v (1e), have been measured. ,, The wavenumbers of the vibrations of the (ionically bonded) M–F units compare acceptably well with the calculated values, as presented in Table ; that is, the calculated wavenumbers are a little larger, with a common empirical scaling factor of 0.97(3). A 1–2% of the 3% discrepancy is due to the harmonic approximation . For the heavier halogens from Br on, the calculated intensities of the metal–halogen stretching vibrations are predicted to be significantly weaker and cannot be easily measured.…”

Antibacterial activities and photocatalyzed degradation of textile dyeing waste water by Mn and F co-doped TiO2nanoparticles

“…Mn−F 3 band is also observed around 680 cm −1 . The peaks observed in the range 730-780 cm −1 can be assigned to Mn−F stretching [30] and the peaks of Mn-F 3 are observed around 630 cm −1 . The peak at 692 cm −1 in TMF5 is shifted to 702 cm −1 in TMF15 due to Ti−F vibration [31].…”