Electrophilic Impact of High-Oxidation State Main-Group Metal and Ligands on Alkane C–H Activation and Functionalization Reactions

High-oxidation
state main-group metal complexes are potential alternatives to transition
metals for electrophilic alkane C–H functionalization reactions.
However, there is little known about how selection of the p-block,
main-group metal and ligand impact alkane C–H activation and
functionalization thermodynamics and reactivity. This work reports
density functional theory calculations used to determine qualitative
and quantitative features of C–H activation and metal-methyl
functionalization energy landscapes for reaction between high-oxidation
state d10s0 InIII, TlIII, SnIV, and PbIV carboxylate complexes with
methane. While the main-group metal influences the C–H activation
barrier height in a periodic manner, the carboxylate ligand has a
much larger quantitative impact on C–H activation with stabilized
carboxylate anions inducing the lowest barriers. For metal-methyl
reductive functionalization reactions, the main-group metal dramatically
influences the barrier heights, which are correlated to reaction thermodynamics
and bond heterolysis energies as a model for two-electron reduction
energies. Overall, this work begins to outline which main-group metals
and carboxylate ligands could be useful for alkane functionalization
systems that utilize electrophilic C–H activation and metal-alkyl
functionalization reactions.