Reverse Arene Sandwich Structures Based upon π‐Hole⋅⋅⋅[MII] (d8 M=Pt, Pd) Interactions, where Positively Charged Metal Centers Play the Role of a Nucleophile.

The complexes [Pt(tpp)] (H2tpp=tetraphenylporphyrin), [M(acac)2] (M=Pd, Pt, Hacac=acetylacetone), and [Pd(ba)2] (Hba=benzoylacetone) were co‐crystallized with highly electron‐deficient arene systems to form reverse arene sandwich structures built by π‐hole⋅⋅⋅[MII] (d8M=Pt, Pd) interactions. The adduct [Pt(tpp)]⋅2 C6F6 is monomeric, whereas the diketonate 1:1 adducts form columnar infinity 1D‐stack assembled by simultaneous action of both π‐hole⋅⋅⋅[MII] and C⋅⋅⋅F interactions. The reverse sandwiches are based on noncovalent interactions and calculated ESP distributions indicate that in π‐hole⋅⋅⋅[MII] contacts, [MII] plays the role of a nucleophile. Role reversal: Square‐planar platinum(II) and palladium(II) systems with π hole‐donating polyfluoroaromatic species give a family of reverse sandwich structures based on noncovalent interactions in which the charge distribution at the metal center and at arenes is opposite to that of classic sandwich species. [ABSTRACT FROM AUTHOR]