Correction to “Intrinsic Reactivity of Diatomic 3d Transition-Metal Carbides in the Thermal Activation of Methane: Striking Electronic Structure Effects”

Mechanistic aspects of the C–H bond activation of methane by metal-carbide cations MC+ of the 3d transition-metals Sc-Zn were elucidated by NEVPT2//CASSCF quantum-chemical calculations and verified experimentally for M = Ti, V, Fe, and Cu by using Fourier transform ion-cyclotron resonance mass spectrometry. While MC+ species with M = Sc, Ti, V, Cr, Cu, and Zn activate CH4 at ambient temperature, this is prevented with carbide cations of M = Mn, Fe, and Co by high apparent barriers; NiC+ has a small apparent barrier. Hydrogen-atom transfers from methane to metal-carbide cations were found to proceed via a proton-coupled electron transfer mechanism for M = Sc-Co; wherein the doubly occupied πxz/yz-orbitals between metal and carbon at the carbon site serve as electron donors and the corresponding metal-centered vacant π*xz/yz-orbitals as electron acceptors. Classical hydrogen-atom transfer transpires only in the case of NiC+, while ZnC+ follows a mechanistic scenario, in which a formally hydridic hydrogen is...