Halogenated closo‐Dodecaborate Anions Stabilize Weakly Bound [(Me3NH)3X]2+ (X = Cl, Br) Dications in the Solid State. Issue 38 (21st August 2017) - Bolli, Christoph
Abstract : Cocrystallization of [Me3 NH]2 [B12 Y12 ] (Y = Cl, Br, I) with 1 equiv. of [Me3 NH]X (X = Cl, Br) from acetonitrile/diethyl ether solution produced large colorless single crystals of [(Me3 NH)3 X][B12 Y12 ]. Four different compounds of this type were prepared and structurally characterized. The compounds consist of weakly coordinating perhalogenated closo ‐dodecaborate [B12 Y12 ] 2– dianions and unprecedented weakly bound discrete [(Me3 NH)3 X] 2+ dications. The [(Me3 NH)3 X] 2+ dications are built up from a central halide anion and three [Me3 NH] + cations bound by N–H··· X hydrogen bonds. The cations have a pyramidal structure, as determined by X‐ray diffraction, which is in contrast to quantum‐chemical calculations, which predict a trigonal‐planar structure. While the [(Me3 NH)3 Cl] 2+ and [(Me3 NH)3 Br] 2+ cations were easily prepared, attempts to synthesize the corresponding [(Me3 NH)3 F] 2+ and [(Me3 NH)3 I] 2+ cations failed. Three further crystal structures containing the angulated [(Me3 NH)2 X] + cation stabilized by [B12 Cl12 ] 2–, [B12 Br12 ] 2–, or [Me3 NB12 Cl11 ] – are reported as well. Abstract : Unprecedented [(Me3 NH)3 X] 2+ dications are lattice‐stabilized in the solid state by perhalogenated closo ‐dodecaborates. Syntheses of the materials and their crystal structures are discussed and compared with the results of quantum‐chemical calculations.