Gauche and trans ethylenediammonium in the structures of ethylenediammonium tetrafluoroborate and tetrafluoroborate-fluoride crystals
Year: 2025
Type: article
Abstract: 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 [ en H 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 $${\text{R}}_{2}^{1}(7)$$ R 2 1 ( 7 ) [ en H 2 ]F + fragment through hydrogen bonding with the fluoride anion. Three such $${\text{R}}_{2}^{1}(7)$$ R 2 1 ( 7 ) [ en H 2 ]F + fragments, along with a fluoride anion from a fourth [ en H 2 ]F + unit, associate into a more complex $${\text{R}}_{8}^{4}(16)$$ R 8 4 ( 16 ) ring motif within the hydrogen-bonded network of [ en H 2 ](BF 4 )F. In the [ en H 2 ](BF 4 ) 2 salt, the ethylenediammonium dications adopt a trans configuration, corresponding to C 2 h point group symmetry. Raman and IR spectra were recorded and tentatively interpreted. A clear spectroscopic distinction between the trans and gauche conformations of the $${\mathbf{e}\mathbf{n}\text{H}}_{2}^{2+}$$ e n H 2 2 + dication was observed and discussed.
Source: Structural Chemistry
Authors: Andrii Vakulka, Evgeny Goreshnik
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,990
OpenAlex ID: W4413129138