Formal Metal-Dependent (M = Pt, Pd) Switching between Arene π-Hole and σ-(Te)-Hole in the Arenetellurium(II) Noncovalent Binding

The diketonate complexes M(acac)2 (M = Pd (1), Pt (2)) were cocrystallized with bis(perfluoropyridin-4-yl)tellane (PyF2Te). Single-crystal X-ray studies of the resulting adducts revealed that the binding mode and stoichiometry between the coformers dramatically depend on the identity of metal sites. Pd(acac)2 formed adduct 13·(PyF2Te)2 where Te···Cacac and πhole···Pd noncovalent interactions were detected. In contrast to 1, Pt(acac)2 formed adduct 2·PyF2Te where the Te···Pt metal-involving chalcogen bond was observed. Various DFT methods, including the calculation of fully optimized dimeric assemblies and their mutated dimers, allowed for a detailed examination of the corresponding metal-involving noncovalent interactions. Our findings support the notion that metal-involving interactions are the primary structure-determining factors, and the formal transition to the Te···Pt chalcogen bond can be attributed to the increased dz2-nucleophilicity of the platinum atom compared to the palladium site.