Synthesis and crystal structures of two 1,3-di(alk-yloxy)-2-(methyl-sulfan-yl)imidazolium tetra-fluorido-borates

Thomas Gelbrich; Martin Lampl; Gerhard Laus; Volker Kahlenberg; Hubert Huppertz; Herwig Schottenberger

doi:10.1107/S2056989020003643

Synthesis and crystal structures of two 1,3-di(alk-yloxy)-2-(methyl-sulfan-yl)imidazolium tetra-fluorido-borates

Acta Crystallogr E Crystallogr Commun. 2020 Mar 17;76(Pt 4):552-556. doi: 10.1107/S2056989020003643. eCollection 2020 Apr 1.

Authors

Thomas Gelbrich¹, Martin Lampl², Gerhard Laus², Volker Kahlenberg³, Hubert Huppertz², Herwig Schottenberger²

Affiliations

¹ University of Innsbruck, Institute of Pharmacy, Innrain 52, 6020 Innsbruck, Austria.
² University of Innsbruck, Faculty of Chemistry and Pharmacy, Innrain 80-82, 6020 Innsbruck, Austria.
³ University of Innsbruck, Institute of Mineralogy and Petrography, Innrain 52, 6020 Innsbruck, Austria.

Abstract

Two salts were prepared by methyl-ation of the respective imidazoline-2-thione at the sulfur atom, using Meerwein's salt (tri-methyl-oxonium tetra-fluorido-borate) in CH₂Cl₂. 1,3-Dimeth-oxy-2-(methyl-sulfan-yl)imidazolium tetra-fluorido-borate (1), C₆H₁₁N₂O₂S⁺·BF₄ ^-, displays a syn conformation of its two meth-oxy groups relative to each other whereas the two benz-yloxy groups present in 1,3-dibenz-yloxy-2-(methyl-sulfan-yl)imidazolium tetra-fluorido-borate (2), C₁₈H₁₉N₂O₂S⁺·BF₄ ^-, adopt an anti conformation. In the mol-ecules of 1 and 2, the methyl-sulfanyl group is rotated out of the plane of the respective heterocyclic ring. In both crystal structures, inter-molecular inter-actions are dominated by C-H⋯F-B contacts, leading to three-dimensional networks. The tetra-fluorido-borate counter-ion of 2 is disordered over three orientations (occupancy ratio 0.42:0.34:0.24), which are related by rotation about one of the B-F bonds.

Keywords: conformation; crystal structure; imidazole; methylsulfanyl heterocycle; tetrafluoridoborate.