Synthesis, Structure and Chemical Bonding of Polyantimony Clusters Containing Coinage Metals [M2Sb14]4– (M = Cu, Ag)

Comprehensive Summary Binary polyantimony clusters, namely [Cu2Sb14]4– and [Ag2Sb14]4–, containing coinage metals, were successfully synthesized and characterized, in which two homoatomic Sb73– subunits are bridged by two coinage metals in η4:η1 and η1:η1 coordination modes, respectively. In [Cu2Sb14]4–, two bridging Cu ions and two Sb atoms form a planar rhombic unit, which was revealed to have antiaromatic properties by theoretical calculations. Further electron structure and bonding analysis confirmed the presence of delocalized bonds in the rhombic unit and the metallophilic interaction between two formal M+ ions. Two bimetallic Cu/Ag‐Sb clusters, [Cu2Sb14]4− and [Ag2Sb14]4−, comprising intact Sb7 units, were successfully synthesized and characterized. Quantum chemical calculations reveal that the rhombic Cu2Sb2 units within the [Cu2Sb14]4− cluster exhibit σ‐antiaromatic properties, and additional bonding analysis demonstrates that Cu∙∙∙Cu or Ag∙∙∙Ag interactions can be characterized as metallophilic interactions.