High-valent late transition metal oxo compounds attracted attention because of their peculiar metal–oxygen bond. Their oxo ligands exhibit an electrophilic and distinct radical oxyl (O˙−) rather than the more common nucleophilic (O2−) character.
Matrix isolation is a fundamental tool for the synthesis and characterization of highly reactive novel species and investigation of unusual bonding situations. Ab initio descriptions of guest-host interactions in matrix isolation are highly demanding, as the weak interactions between guest and host can influence the former's oftentimes challenging electronic structure. In this study, the matrix effects on a single CO 2 molecule in an argon matrix were investigated with dispersion-corrected density functional theory calculations. Three different guest-host structures were described by bulk models employing periodic boundary conditions as well as cluster models. The calculations were analyzed with respect to structural features of the CO 2 molecule and its immediate surroundings. Also, the molecule's harmonic frequencies were determined. The calculated frequencies were in qualitative agreement with experimental observations. The cluster models produced comparable results given that the clusters were large enough to reproduce the structural features of the bulk model.
Electrochemical fluorination in anhydrous HF, also known as the Simons process, is a widely used industrial method for fluorination of organic compounds. Its mechanism, being not so well understood, has long been debated and is believed to involve higher valent nickel fluorides formed on the nickel-plated anode during the process. One of these is speculated to be Ni2F5, which was previously reported in the literature and assigned via infrared spectroscopy, but its crystal structure is not yet known. We have identified known crystal structures of compounds with similar stoichiometries as Ni2F5 and utilized them as a starting point for our periodic DFT investigations, applying the PBE+U method. Ni2F5 as the most stable polymorph was found to be of the same crystal structure as another mixed valent fluoride, Cr2F5. The calculated lattice parameters are a = 7.24 Å, b = 7.40 Å, c = 7.08 Å and β = 118.9° with an antiferromagnetic ordering of the nickel magnetic moments.
An important synthetic route for the fluorinated organic compounds is electrochemical fluorination (ECF). This is a process taking place on a nickel anode immersed in anhydrous HF. Even though the mechanism is not fully resolved, it is believed that it involves higher valent nickel fluorides formed on the anode. One such compound could be NiF4. Its synthesis and existence have been reported in the literature. However, its crystal structure has so far remained unknown. In this paper, we present, for the first time, the theoretical study of the possible crystal structure of NiF4. We investigated six crystal structures of known metal tetrafluorides as possible candidates for NiF4 by periodic DFT, with the PBE+U method. Of the investigated structures, the most stable polymorph of NiF4 was found to be of the same crystal structure as RuF4. The unit cell parameters were calculated to be a = 4.80 Å, b = 5.14 Å, c = 5.18 Å and β = 105.26∘. All but one of the investigated structures feature octahedrally coordinated nickel centers with two non-bridging fluorine atoms. In the structure originating from ZrF4, all six fluorine atoms around the nickel centers are bridging and two are located in the vacancies around the nickel skeleton, not directly bound to nickel. The overall magnetic arrangement in all the investigated structures is antiferromagnetic. A comparison with other binary nickel fluorides supports the experimental findings that NiF4 is thermodynamically the least stable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.