Studying structurally related families of compounds is a valuable tool in understanding and predicting material properties and has been extensively used for metal halide perovskites. Due to the variable anion structures in group 15 halogenido metalates, similar family relations are still largely missing. Herein, we present compounds featuring the [Sb2nI6n+4]4− family of anions, including the first n=5 member in [Hpyz]4[Sb10I34] (Hpyz=pyrazinium), which contains the largest halogenido pentelate anion reported to date. The optical properties of compounds featuring n=1–5 anions show a clear trend as well as an outlier, a low band gap of 1.72 eV for [Hpyz]4[Sb10I34], that can be well understood using quantum chemical investigations. Also using SbI3 and [H2NMe2]3[SbI6], a compound featuring a single octahedral [SbI6]3− unit, as limiting cases, we show that structure‐property relationships can be established in group 15 halogenido metalates in a similar way as in metal halide perovskites, thus providing a framework for understanding new and known compounds in this emerging class of materials.

The synthesis and characterization of a new silver iodido bismuthate with a low optical band gap highlights the decisive role of building unit connectivity for the optical properties in this class of materials.

Thirteen neutral complexes [E x M y X z -(PPh 3 ) n (L) m ] (E = Bi, Sb; M = Cu, Ag; X = Cl, Br, I; L = solvent) featuring three different motifs were prepared and characterized regarding their structure, stability, and absorption spectra. While not identical in structural motif, the compounds can serve as models for the influence of the composition E/M/X on the optical properties of double perovskites A 2 EMX 6 (A = Cs, CH 3 NH 3 ).

A new copper iodido bismuthate with a low band gap of 1.59 eV and good thermal and air stability was prepared via a simple solution-based route.

The electronic situation at the copper atom controls the optical properties in a series of multinary iodido antimonates and bismuthates.