Gauche and trans ethylenediammonium in the structures of ethylenediammonium tetrafluoroborate and tetrafluoroborate‑fluoride crystals

Vakulka, Andrii (author), Goreshnik, Evgeny A. (author)

The possible stereochemical conformations of the isolated ethylenediammonium dication were discussed, along with an assessment of their relative stabilities. Crystals of ethylenediammonium tetrafluoroborate-fluoride and tetrafluoroborate salts were prepared and structurally characterised. The crystal packing and hydrogen bonding interactions involving the ethylenediammonium dication were also described and analysed. In the structure of [enH$_2$](BF$_4$)F, the ethylenediammonium dication adopts a superposition of left-handed and right-handed C$_2$-symmetrical gauche (synclinal) conformations, with an NCCN torsion angle of ±75.49(10)°. These conformers form a cyclic R$^1_2$(7) [enH$_2$]F$^+$ fragment through hydrogen bonding with the fluoride anion. Three such R$^1_2$(7) [enH$_2$]F$^+$ fragments, along with a fluoride anion from a fourth [enH$_2$]F$^+$ unit, associate into a more complex R$^4_8$(16) ring motif within the hydrogen-bonded network of [enH$_2$](BF$_4$)F. In the [enH$_2$](BF$_4$)$_2$ salt, the ethylenediammonium dications adopt a trans configuration, corresponding to C$_{2h}$ point group symmetry. Raman and IR spectra were recorded and tentatively interpreted. A clear spectroscopic distinction between the trans and gauche conformations of the enH$^{2+}_2$ dication was observed and discussed.

• Language: English
• Keywords: ethylenediammonium, Raman spectrum, tetrafluoroborate, fluoride, crystal structure, IR spectrum
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: Str. 81–100
• Numbering: Vol. 37, iss. 1
• PID: 20.500.12556/RUL-178849
• UDC: 54
• ISSN on article: 1572-9001
• DOI: 10.1007/s11224-025-02579-3
• COBISS.SI-ID: 245833987
• Publication date in RUL: 30.01.2026

Record is a part of a journal

• Title: Structural chemistry
• Shortened title: Struct. chem.
• Publisher: Springer Nature
• ISSN: 1572-9001
• COBISS.SI-ID: 513246233

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: borati, fluoridi, kristalna struktura, infrardeči spektri, stereokemija

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P1-0045
• Name: Anorganska kemija in tehnologija