Solution Behavior of Beryllium Halides in Dimethylformamide

The reactivity of beryllium compounds in N,N-dimethylformamide (DMF) is fairly uncharted. However, as a versatile O-donor solvent, DMF enables reaction conditions that are inaccessible in solvents more commonly applied in beryllium chemistry. Here we present a comprehensive study on the interaction of beryllium halides BeX2 (X = F, Cl, Br, I) with DMF. Through NMR and IR spectroscopy as well as single-crystal X-ray diffraction, we were able to characterize several Be(DMF)(1-4)X-2 species and distinguish the competitiveness of the investigated halides against DMF. On the basis of titration experiments, [BeCl(DMF)(3)](+) was identified as the dominant compound when BeCl2 was dissolved in DMF. The unpredicted high beryllium-halide bond strength in chloro complexes as well as the instability of iodo compounds is discussed. The latter showed a distinctively different coordination chemistry compared to the other beryllium halides. In addition to that, the first example of a compound with the hexaiodidodiberyllate anion ([Be2I6](2-)) was characterized. On the basis of our results, BeBr2 is a superior starting material compared to the other beryllium halides for the synthesis of coordination chemistry compounds.