Vibrational and electronic spectra of molecular chromium tetrafluoride, CrF4, and chromium pentafluoride, CrF5. Comments on the existence of chromium hexafluoride, CrF6

Abstract

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Inexpensive and accurate predictions of optical excitations in transition-metal complexes: the TDDFT/PBE0 route

“…As a ®nal remark, we note that none of the calculated transitions for CrF 6 can be detected in the UV spectrum of CrF 5 [18], thus ruling out the disproportionation mechanism of this species into CrF 4 and CrF 6 .…”

“…Inexpensive and accurate predictions of optical excitations in transition-metal complexes: the TDDFT/PBE0 route and WF 6 [13±15], together with detailed experimental data [16,17], whereas the existence of CrF 6 is still a matter of discussion [18,19]. In this last case, theoretical predictions of the optical spectrum could give some hints to experimentalists for the identi®cation of such a species.…”

In situ Raman spectroscopy studies on chromium oxide catalyst in an anhydrous hydrogen fluoride atmosphere

“…The vibrational band of ν(CrF) in the fluoride is too weak to be detected by Raman spectroscopy. Jacobs and coworkers reported [32] that the infrared peaks of chromium oxyfluoride are located at 1205 (w), 910 (w), 885 (w), and 555 (m) cm −1 . Since infrared absorption and Raman vibrational bands have certain similarities, it further confirms that the band at 890 cm −1 (α 2 ) could be assigned to ν(CrO) of the CrO 2 F 2 or/and CrOF 3 species.…”

Molecular Structure of Metal Halides

“…493,528 These questions were raised in spectroscopic studies. A further controversy referred to the shape of CrF 6 (see the next section).…”