Ionic-liquid-assisted synthesis of the phosphorus interhalides PBr4IBr2 and PBr4I5Br7

摘要

The phosphorus interhalides PBr4IBr2 (1) and PBr4(2)I5Br7 (2) were prepared by reaction of PBr5 and the interhalogen IBr in the ionic liquid MeBu3NN(Tf)(2) (N(Tf)(2): bis(trifluoromethylsulfonyl)amide). PBr4IBr2 (1) consists of tetrahedral PBr4(+) cations and linear IBr2(-) anions. PBr4(2)I5Br7 (2) also contains PBr4(+) cations as well as the iodine bromide anion I5Br7(2-). The latter represents the yet largest known polyiodinebromide. Moreover, (2) shows remarkable halogen release (IBr and Br-2) of 96.8 wt below 300 degrees C. For the ternary system P-Br-I, (1) and (2) are the first compounds that were characterized by crystal structure analysis. Composition, bonding situation and properties were further validated by energy dispersive X-ray (EDX) analysis, thermogravimetry (TG) and Raman spectroscopy.