The Intermetalloid Clusters [Ni2Bi12]4+ and [Rh2Bi12]4+ – Ionothermal Synthesis,Crystal Structures,and Chemical Bonding

The intermetalloid clusters [M₂Bi₁₂]⁴⁺ (M = Ni, Rh) were synthesized as halogenido‐aluminates in Lewis‐acidic ionic liquids. The reaction of bismuth and NiCl₂ in [BMIm]Cl · 5AlCl₃ (BMIm = 1‐butyl‐3‐methylimidazolium) at 180 °C yielded black, triclinic (P1 ) crystals of [Ni₂Bi₁₂][AlCl₄]₃[Al₂Cl₇]. Black, monoclinic (P2₁/m) crystals of [Rh₂Bi₁₂][AlBr₄]₄ precipitated after dissolving the cluster salt Bi_12–xRhX_13–x (X = Cl, Br; 0 < x < 1) in [BMIm]Br·4.1AlBr₃ at 140 °C. In the cationic cluster [Ni₂Bi₁₂]⁴⁺, the nickel atoms center two base‐sharing square antiprisms of bismuth atoms (symmetry close to D_4h). The valence‐electron‐poorer rhodium‐containing cluster is a distorted variant of this motif: the terminating Bi₄ rings are folded to bicyclic “butterflies“ and the central square splits into two dumbbells (symmetry close to D_2h). DFT‐based calculations and real‐space bonding analyses place the intermetalloid units between a triple‐decker complex and a conjoined Wade‐Mingos cluster.