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

Abstract

The diketonate complexes M(acac) 2 (M = Pd ( 1 ), Pt ( 2 )) were cocrystallized with bis(perfluoropyridin-4-yl)tellane (Py F 2 Te). 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 1 3 ·(Py F 2 Te) 2 where Te···C acac and π hole ···Pd noncovalent interactions were detected. In contrast to 1, Pt(acac) 2 formed adduct 2 ·Py F 2 Te 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 d z 2 -nucleophilicity of the platinum atom compared to the palladium site.