Owing to the strong nonpolar bonds involved, selective C−H functionalization of methane and ethane to esters remains a challenge for molecular homogeneous chemistry. We report that the computationally predicted main‐group p‐block SbV(TFA)5 complex selectively functionalizes the C−H bonds of methane and ethane to the corresponding mono and/or diol trifluoroacetate esters at 110–180 °C with yields for ethane of up to 60 % with over 90 % selectivity. Experimental and computational studies support a unique mechanism that involves SbV‐mediated C−H activation followed by functionalization of a SbV‐alkyl intermediate.

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 d 10 s 0 In III , Tl III , Sn IV , and Pb IV 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.

SbVF5 is generally assumed to oxidize methane through a methanium-to-methyl cation mechanism.

M06 density functional theory calculations reveal that arene C−H functionalization by the p-block main-groupmetal complex Tl III (TFA) 3 (TFA = trifluoroacetate) occurs by a C−H activation mechanism akin to transition-metal-mediated C− H activation. For benzene, toluene, and xylenes a one-step C−H activation is preferred over electron transfer or proton-coupled electron transfer. The proposed C−H activation mechanism is consistent with calculation and comparison to experiment, of arene thallation rates, regioselectivity, and H/D kinetic isotope effects. For tetramethyl-and pentamethyl-substituted arenes, electron transfer becomes a competitive pathway and thermodynamic and kinetic calculations correctly predict the experimentally reported electron transfer crossover region. These calculations show that p-block metals activate strong hydrocarbon C−H bonds through organometallic intermediates and changes in arene functional groups can result in a shift from C−H activation to electron transfer.

Alkane CH activation is a fundamental reaction class where a metalligand complex reacts with a CH bond to give a metal-alkyl organometallic intermediate. CH activation reactions have been reported for a variety of transition metals and main-group metals. This chapter highlights recent quantum-mechanical studies that have used energy decomposition analysis (EDA) to provide insight into σ-coordination complexes and transition states for alkane CH activation reactions. These studies have provided new conceptual understanding of CH activation reactions and detailed insight into the physical nature and magnitude of interaction between alkanes with transition metals and main-group metals.