Arsen(III)‐, Antimon(III)‐ und Bismuth(III)‐halogenid‐Komplexe des [2.2.2]Paracyclophans: Vom lockeren van‐der‐Waals‐Addukt zu stark gerichteten π‐Komplexen mit zwei‐ und dreifacher externer η⁶‐Koordination

Arsenic(III), Antimony(III), and Bismuth(III) Trihalide Complexes of [2.2.2]Paracyclophane: From Weak van der Waals Coordination to Strongly Directional π Complexation with Single or Double External η⁶ Coordination [2.2.2]Paracyclophane forms the adducts C₂₄H₂₄·AsCl₃ (1), C₂₄H₂₄·(SbCl₃)₂·1/2 C₆H₆ (2), and C₂₄H₂₄·(BiCl₃)₃·C₆H₆ (3). For solutions in polar solvents NMR spectra indicate extensive dissociation and/or fluxionality. In the crystals adduct 1 features a weak addition of the AsCl₃ molecule to one open side of a paracyclophane molecule with long intermolecular contacts approaching C_3v symmetry. – Crystalline 2 shows SbCl₃ coordination to two of the benzene rings of the hydrocarbon in a quasi‐centered η⁶ mode, while one of the benzene rings remains uncoordinated. Chlorine‐bridging between antimony atoms leads to tetrameric units (SbCI₃)₄ in the lattice. – In the bismuth compound 3 each benzene ring of the hydrocarbon is engaged in centroid (η⁶)π complexation, with the BiCl₃ units crosslinked by chlorine bridges. The average of the Bi–ring distances (3.08,2.98, and 2.99 Å) is shorter than for the Sb–ring distances in 2 (3.047 and 3.050 Å), indicating stronger bonding. The crystal benzene is not coordinating.