Flash Communication: Density Functional Theory (DFT) Calculations Indicate an Unconventional Anagostic Complex for the Initial Stage of the Reported Sc3+ Boosted C–H Bond Activation of 3,4-Dimethoxyacetanilide with Pd(OAc)2

Abstract

Structural details for the complex [(3,4-dimethoxyacetanilide)(MeCN)Pd(OAc)₂Sc(Otf)₃] obtained from Density Functional Theory calculations indicate that with a three-atom tether coordination, the ligand aromatic ring lies in an above-plane position where steric constraints within the molecule give rise to a nonrotational anagostic-like complex where the C–H bond electron density does not penetrate the palladium core. Hirschfeld-based Independent Gradient Method partition and Natural Bond Orbital analyses confirm that there is no η²-π-donation or agostic interaction. When the MeCN ligand is removed from the complex, energy minimization results in the ring moving into the plane and an η¹-σ-bonded complex results where weak agostic donation from an aromatic ring ortho-C–H bond occurs.