First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures
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...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2022-11-01
|
| Series: | Crystals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4352/12/11/1640 |
| _version_ | 1797465552441049088 |
|---|---|
| author | Tilen Lindič Anthony Schulz Beate Paulus |
| author_facet | Tilen Lindič Anthony Schulz Beate Paulus |
| author_sort | Tilen Lindič |
| collection | DOAJ |
| description | 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 NiF<sub>4</sub>. 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 NiF<sub>4</sub>. We investigated six crystal structures of known metal tetrafluorides as possible candidates for NiF<sub>4</sub> by periodic DFT, with the PBE+U method. Of the investigated structures, the most stable polymorph of NiF<sub>4</sub> was found to be of the same crystal structure as RuF<sub>4</sub>. The unit cell parameters were calculated to be a = 4.80 Å, b = 5.14 Å, c = 5.18 Å and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> = 105.26<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>. All but one of the investigated structures feature octahedrally coordinated nickel centers with two non-bridging fluorine atoms. In the structure originating from ZrF<sub>4</sub>, 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 NiF<sub>4</sub> is thermodynamically the least stable. |
| first_indexed | 2024-03-09T18:24:07Z |
| format | Article |
| id | doaj.art-0a7f238c58584a688824ae99540a8627 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-09T18:24:07Z |
| publishDate | 2022-11-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-0a7f238c58584a688824ae99540a86272023-11-24T08:02:19ZengMDPI AGCrystals2073-43522022-11-011211164010.3390/cryst12111640First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal StructuresTilen Lindič0Anthony Schulz1Beate Paulus2Institute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, GermanyInstitute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, GermanyInstitute for Chemistry and Biochemistry, Freie Universität Berlin, Arnimallee 22, 14195 Berlin, GermanyAn 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 NiF<sub>4</sub>. 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 NiF<sub>4</sub>. We investigated six crystal structures of known metal tetrafluorides as possible candidates for NiF<sub>4</sub> by periodic DFT, with the PBE+U method. Of the investigated structures, the most stable polymorph of NiF<sub>4</sub> was found to be of the same crystal structure as RuF<sub>4</sub>. The unit cell parameters were calculated to be a = 4.80 Å, b = 5.14 Å, c = 5.18 Å and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>β</mi></semantics></math></inline-formula> = 105.26<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mrow></mrow><mo>∘</mo></msup></semantics></math></inline-formula>. All but one of the investigated structures feature octahedrally coordinated nickel centers with two non-bridging fluorine atoms. In the structure originating from ZrF<sub>4</sub>, 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 NiF<sub>4</sub> is thermodynamically the least stable.https://www.mdpi.com/2073-4352/12/11/1640NiF<sub>4</sub>periodic DFTinvestigating unknown crystal structure |
| spellingShingle | Tilen Lindič Anthony Schulz Beate Paulus First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures Crystals NiF<sub>4</sub> periodic DFT investigating unknown crystal structure |
| title | First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures |
| title_full | First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures |
| title_fullStr | First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures |
| title_full_unstemmed | First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures |
| title_short | First-Principle Investigation of Hypothetical NiF<sub>4</sub> Crystal Structures |
| title_sort | first principle investigation of hypothetical nif sub 4 sub crystal structures |
| topic | NiF<sub>4</sub> periodic DFT investigating unknown crystal structure |
| url | https://www.mdpi.com/2073-4352/12/11/1640 |
| work_keys_str_mv | AT tilenlindic firstprincipleinvestigationofhypotheticalnifsub4subcrystalstructures AT anthonyschulz firstprincipleinvestigationofhypotheticalnifsub4subcrystalstructures AT beatepaulus firstprincipleinvestigationofhypotheticalnifsub4subcrystalstructures |