AbstractThe crystal structure of 2,2'‐bipyridinium pentabromoantimonate (III), (2,2'‐C10H8N2H2)SbBr5, was determined (T = 297 K): C2h5‐P21/c, Z = 8, a = 1457.5 pm, b = 1472.6 pm, c = 1677.5 pm, β = 110.34°, Rw(F) = 0.057. Characteristic for the structure is the tetrameric anion {[SbBr5]2⊖}4. No 79,81Br NQR could be observed in this compound. The crystal structure of 4,4'‐bipyridinium pentabromoantimonate (III), (4,4'‐C10H8N2H2)SbBr5, was also studied (T = 300 K): Ci1‐P1, Z = 2, a = 1128.7 pm, b = 1012.1 pm, c = 854.8 pm, α = 98.94°, β = 101.06°, γ = 113.57°, Rw(F) = 0.052. Characteristic for the structure of this compound is the dimeric anion {[SbBr5]2⊖}2. The 81Br NQR spectrum of 4,4'‐bipyridinium pentabromoantimonate (III) was studied in the temperature range 77 ≤ T/K ≤ 300. A five line spectrum is present over the whole temperature range covered. The 81Br NQR frequencies are spread out over a wide range; at 77 K: 34 ≤ v(81Br)/MHz ≤ 113. 81Br NQR spectrum and crystal structure of 4,4'‐bipyridinium pentabromoantimonate (III) are discussed and a model for both, the temperature dependence of the NQR frequencies and of their spread is given as is an assignment: Position of the Br atom in the complex anion ↔ 81Br NQR frequency.