The Intermetalloid Clusters [Ni 2 Bi 12 ] 4+ and [Rh 2 Bi 12 ] 4+ – Ionothermal Synthesis, Crystal Structures, and Chemical Bonding

The intermetalloid clusters [ M 2 Bi 12 ] 4+ ( M = Ni, Rh) were synthesized as halogenido‐aluminates in Lewis‐acidic ionic liquids. The reaction of bismuth and NiCl 2 in [BMIm]Cl · 5AlCl 3 (BMIm = 1‐butyl‐3‐methylimidazolium) at 180 °C yielded black, triclinic ( P 1 ) crystals of [Ni 2 Bi 12 ][AlCl 4 ] 3 [Al 2 Cl 7 ]. Black, monoclinic ( P 2 1 / m ) crystals of [Rh 2 Bi 12 ][AlBr 4 ] 4 precipitated after dissolving the cluster salt Bi 12– x Rh X 13– x ( X = Cl, Br; 0 < x < 1) in [BMIm]Br·4.1AlBr 3 at 140 °C. In the cationic cluster [Ni 2 Bi 12 ] 4+ , the nickel atoms center two base‐sharing square antiprisms of bismuth atoms (symmetry close to D 4 h ). The valence‐electron‐poorer rhodium‐containing cluster is a distorted variant of this motif: the terminating Bi 4 rings are folded to bicyclic “butterflies“ and the central square splits into two dumbbells (symmetry close to D 2 h ). DFT‐based calculations and real‐space bonding analyses place the intermetalloid units between a triple‐decker complex and a conjoined Wade‐Mingos cluster.