Recently, halogen bonding (XB) has been defined by IUPAC as an attractive intermolecular interaction between an activated halogen atom which develops a charge-deficient area (σ-hole) in the prolongation of the C−X bond, and Lewis bases. The extension to divalent chalcogen atoms (Se, Te) toward efficient and directional chalcogen bonding (ChB) interaction represents a true challenge as the strong directionality of XB is hampered then by the presence of possibly two σ-holes in the prolongation of the two C−Ch bonds. Following our first results involving organic selenocyanates (Chem. Commun. 2017, Cryst. Growth Des. 2019), we have developed in parallel two approaches to activate only one strong σ-hole on chalcogen atoms, in collaboration with Nancy colleagues involved in the modelization of electrostatic potential surfaces.
The first approach is based on the known electron-withdrawing effect of carboranes on substituents introduced on the carbon atoms. Specifically here, in collaboration with Korean colleagues, icosahedral ortho-carboranes substituted with two methylseleno or methyltelluro groups were prepared and shown to interact strongly with halide anions as Lewis bases through short and directional Se(Te)•••X− ChB interactions. The new diodo analog 1,2-I2C2B10H10 also appears as an extremely powerful XB donor.
The second approach extends the known efficiency of iodoacetylene derivatives as XB donors, to analogous methylseleno- or methyltelluro-acetylene derivatives. Their syntheses allowed for the formation of co-crystals with neutral Lewis bases such as 4,4’-bipyridine. Strong C≡C−Te•••Npy ChB interactions were found, with a Te•••N distance below 80% of the van der Waals contact distance.
Both successful approaches give the crystal engineering community new tools to use ChB interactions, for anion recognition processes, catalysis and in materials science.
These projects have received funding from ANR under grant agreements ANR-17-ERC3-0003 (MOLFERRO, I.-R. Jeon) and ANR-17-CE07-0025-02 (SIGMA-HOLE, M. Fourmigué), the Région Bretagne (½ PhD grant), together with Campus France PHC STAR (No 41595RK) and the National Research Foundation of Korea (NRF-2018K1A3A1A21043478).
Ie-Rang Jeon & Marc Fourmigué, Univ Rennes, CNRS, ISCR-6226, F-35000 Rennes, France
ie-rang-jeonuniv-rennes1 [dot] fr, marc [dot] fourmigueuniv-rennes1 [dot] fr
- Strong σ-hole activation on icosahedral carborane derivatives for a directional halide recognition
Maxime Beau, Sunhee Lee, Sooyeon Kim, Won-Sik Han, Olivier Jeannin, Marc Fourmigué,* Emmanuel Aubert, Enrique Espinosa, and Ie-Rang Jeon*
Angew. Chem. Int. Ed., 2020, in press, https://doi.org/10.1002/anie.202010462
- Activating chalcogen bonding (ChB) in alkylseleno/ alkyltelluroacetylenes toward ChB directionality
Arun Dhaka, Olivier Jeannin, Ie-Rang Jeon, Emmanuel Aubert, Enrique Espinosa and Marc Fourmigué*
Angew. Chem. Int. Ed., 2020, in press, https://doi.org/10.1002/anie.202011981
Published Nov. 03, 2020