cyclo‐P4 Building Blocks: Achieving Non‐Classical Fullerene Topology and Beyond

The cyclo‐P₄ complexes [Cp^RTa(CO)₂(η⁴‐P₄)] (Cp^R: Cp′′=1,3‐C₅H₃tBu₂, Cp′′′=1,2,4‐C₅H₂tBu₃) turned out to be predestined for the formation of hollow spherical supramolecules with non‐classical fullerene‐like topology. The resulting assemblies constructed with CuX (X=Cl, Br) showed a highly symmetric 32‐vertex core of solely four‐ and six‐membered rings. In some supramolecules, the inner cavity was occupied by an additional CuX unit. On the other hand, using CuI, two different supramolecules with either peanut‐ or pear‐like shapes and outer diameters in the range of 2–2.5 nm were isolated. Furthermore, the spherical supramolecules containing Cp′′′ ligands at tantalum are soluble in CH₂Cl₂. NMR spectroscopic investigations in solution revealed the formation of isomeric supramolecules owing to the steric hindrance caused by the third tBu group on the Cp′′′ ligand. In addition, a 2D coordination polymer was obtained and structurally characterized.