In5Br7, the second mixed‐valence In(I)—In(II) bromide: In[InBr6]Br. With an appendix on a structure refinement of InBr3

Pale yellow single crystals of In5Br7 grow by sublimation in a temperature gradient of 190 to 100°C under strictly anhydrous conditions from a raw product that is obtained by synproportionation of InBr3 and In (moral ratio 7:8). The structure (monoclinic unit cell; space group Cc; Z = 16; a = 1868.8(2), b = 1860.2(2), c = 1921.7(2) pm, β = 104.19(1)°; Vm = 243.78(5) cm3mol−1) has been solved from single crystal data and contains according to the formulation In [In Br6]Br isolated [In2Br6]2− groups of eclipsed conformation with an averaged In2+In2+ distance of 270 pm. The coordination polyhedra of In+ are highly irregular. Naive coordination numbers (C.N.) are 9 and 10, respectively, with one (C.N. 9) or two (C.N. 10) short distance(s) (≥300 pm) to one or two “lonesome” Br−.