Richard Lagow Excellence Fund in Inorganic Chemistry - Sebastian Hasenstab-Riedel

The Inorganic Seminar Series presents: Sebastian Hasenstab-Riedel 

Richard Lagow Excellence Fund in Inorganic Chemistry

Freie Universität Berlin

Host: Mike Rose

Title: From lab oddities to technical applications: The chemistry of halogens and their compounds 

Location: WEL 2.122

Refreshments served at 3:15pm
 

The incorporation of halogens into molecules or materials confers upon them distinctive functionalities, attributable to the unique properties of these elements. Of special interest are also halogenated moieties, like -OCF₃, -OSF_5, or -OTeF₅. The latter, the so-called teflate group OTeF₅ has been observed to demonstrate electron-withdrawing properties analogous to those of fluorine. Moreover, it is notable for its significantly increased molecular size, which gives rise to distinctive molecular systems when utilized as a ligand.^[1] In addition, it has been recently shown that alterations to such systems can result in interesting new systems, as shown by the application of the novel ligand OTeF₃Ph^F₂.^[2] Based on these ligands, several novel superacidic Brønsted^[3] and Lewis^[4] systems have been developed. These systems have enabled the preparation of surprisingly powerful small molecules, including e.g. fluorinated halonium^[5] or tritylium ions^[6,7].

The second halogen of the periodic table and the most industrially relevant one, chlorine, is an ideal building block for chemicals and materials. Recent developments in the field of chlorine chemistry have opened up new possibilities for the preparation of novel main-group compounds like [SCl₆]^{2– [8]} or [PCl₆]^{– [9]} and, even more importantly, offer unique synthetic pathways for an more sustainable industrial production. This new chlorine technology is based on so-called polychloride anions. The compounds can easily be prepared as solid materials or reactive ionic liquids and show very interesting properties. Therefore, polychlorides have evolved from an area of academic interest to a research topic of industrial potential.^[10]  The inexpensive ionic liquid based on [Cl_n]^– (n = 3-7) shows a similar and sometimes even advantageous reactivity compared to chlorine gas, as exemplified by the synthesis of phosgene^[11], while offering a superior safety profile.^[12] This does not only hold for polychloride systems as other ionic liquids based on polyhalide anions can be prepared as well.^[13,14]

References 

[1] J. Bader et al., Chem. Rev. DOI: 10.1021/acs.chemrev.5c00075 (2025).

[2] D. Wegener et al., JACS Au, DOI: 10.1021/jacsau.5c00577 (2025).

[3] A. Wiesner et al., Angew. Chem. Int. Ed. 56, 8263 (2017). 

[4] L. Fischer et al., Chem. Eur. J. 30, e202403266 (2024). 

[5] L. Fischer et al., Angew. Chem. Int. Ed. 63, e202407497 (2024).

[6] K. F. Hoffmann et al., Angew. Chem. Int. Ed. 61, e202203777 (2022).

[7] J. Schlögl et al., Angew. Chem. Int. Ed. 64, e202423857 (2025).

[8] P. Voßnacker, et al., Angew. Chem. Int. Ed. 61, e202209684 (2022).

[9] M. J. Ernst et al., Chem. Commun., 60, 13372 (2024).

[10] M. Kleoff, et al., Angew. Chem. Int. Ed. 62, e202216586 (2023).

[11] P. Voßnacker et al., Science Advances 7, eabj5186 (2021).

[12] P. Voßnacker et al., ACS Sustainable Chemistry & Engineering 29, 9525 (2021).

[13] K. Sonnenberg et al., Angew. Chem. Int. Ed. 59, 5464 (2020).

[14] G. H. Dreyhsig et al., Science Advances, 10, eadn5353 (2024)