A σ-Poor, π-Rich Pyridonate Pincer Ligand Designed To Enhance C–H Oxidative Addition at Platinum Group Metals: Experimental and Computational Studies

A strong π-donor, weak σ-donor pyridonate pincer complex of platinum is reported, a rare but important electronic ligand structure for promoting C–H activation in late transition metals. Protonation of the complex 2,6-bis(diethylaminomethyl)-4-pyridonate platinum(II) methyl occurs initially at oxygen, with a second proton equivalent affording methane. Methyl triflate similarly methylates initially with oxygen and then platinum. A computational study indicates that this terdentate pyridonate pincer greatly enhances the ability of late transition metals to cleave the C–H bond of methane compared to a classic NCN pincer. With iridium bound to this π-donor pincer, the oxidative addition of methane is computationally predicted to be thermodynamically favorable.