Sb 2 Hg 3 GaBr 4 : A New Supramolecular Framework Structure with [Sb 2 Hg 4/2 ] ±0 Building Blocks Isosteric to Distibane

Sb 2 Hg 3 GaBr 4 is a new air stable transparent reddish solid that crystallizes in space group Pnma (No. 62, Z = 8) with the lattice constants a = 1375.49(8) pm, b = 1269.0(1) pm, c = 1478.19(9) pm. The title compound represents a new structure type based on a cationic framework $^{3}_{\infty}\rm [Sb_{2}Hg_{3}]^{+}$ of a significantly modified Millons base type. Structural building blocks of the cationic partial structure are well known tetrahedral [SbHg 4/2 ] + groups and unprecedented formally neutral [Sb 2 Hg 4/2 ] ±0 units in a 2:1 ratio. The [Sb 2 Hg 4/2 ] ±0 units contain covalent Sb‐Sb bonds (d = 285.6 pm) and are isosteric with Distibane Sb 2 H 4 in a staggered conformation. Structural consequences of the lone pairs located at the Sb atoms of the [Sb 2 Hg 4/2 ] ±0 units are discussed. The charge of the cationic framework is balanced by disordered anions in suitable cavities. They appear as tetrahedral [GaBr 4 ] − but correspond most likely to a superposition of bitetrahedral apex sharing [Ga 2 Br 7 ] − and isolated Br − .