Coordination Variability through Inner-Outer-Sphere Chloride Exchange in Complex Heterometallic Clusters [ <i>M</i> ₂ Bi ₁₄ Cl ₄ ][AlCl ₄ ] ₄ and [ <i>M</i> ₂ Bi ₁₄ Cl <sub>

Five novel heterometallic bismuth-bearing cluster salts within two structural families, monoclinic <i>P</i>2₁/<i>c</i> α-[<i>M</i>₂Bi₁₄Cl₄][<i>Tr</i>Cl₄]₄ and triclinic <i>P</i>1̅ [<i>M</i>₂Bi₁₄Cl₂][AlCl₄]₆ (<i>M</i> = Ru, Os; <i>Tr</i> = Al, Ga), have been discovered via Lewis acidic ionic liquid (LAIL)-assisted synthesis at 180 °C. At the center of both structures is the binuclear inorganic [(Bi₅)<i>M</i>(Bi₄Cl_<i>x</i>)<i>M</i>(Bi₅)]^(4,6)+ cluster cation (<i>x</i> = 2, 4), where the inner-sphere chloride content within the median [Bi₄Cl_<i>x</i>] ring determines the charge of the unit, its symmetry, and the number of outer-sphere [AlCl₄]^- anions required for charge balance. Detailed characterization of the structural relationships, coupled with a comprehensive study of the electronic structure and bonding, indicates the basal-basal Bi-Bi strengthening, apical-basal weakening within [Bi₅]⁺ upon chloride loss, and only minor influence of the transition metal origin on the symmetry of the cluster, besides relatively stronger Os-Os interactions of the two cluster types. These findings indicate inner-outer-sphere chloride exchange in LAILs, controlled by the amount of AlCl₃, and periodic substitutions as viable approaches to control symmetry, bonding, and interconversion in Bi-rich clusters.