Hidden Hydride Transfer as a Decisive Mechanistic Step in the Reactions of the Unligated Gold Carbide [AuC]⁺ with Methane under Ambient Conditions

Abstract

The reactivity of the cationic gold carbide [AuC]+ (bearing an electrophilic carbon atom) towards methane has been studied using Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR‐MS). The product pairs generated, that is, Au+/C2H4, [Au(C2H2)]+/H2, and [C2H3]+/AuH, point to the breaking and making of C−H, C−C, and H−H bonds under single‐collision conditions. The mechanisms of these rather efficient reactions have been elucidated by high‐level quantum‐chemical calculations. As a major result, based on molecular orbital and NBO‐based charge analysis, an unprecedented hydride transfer from methane to the carbon atom of [AuC]+ has been identified as a key step. Also, the origin of this novel mechanistic scenario has been addressed. The mechanistic insights derived from this study may provide guidance for the rational design of carbon‐based catalysts.

The Reactive Sites of Methane Activation: A Comparison of IrC3+ with PtC3+

“…At present, researchers are concerned about the reactions of methane with metal ions such as Os + [ 11 ], Pt + [ 12 ], Ta + [ 13 ] and Rh(0) [ 14 ] and metal oxides such as MgO + [ 15 ], PbO + [ 16 ], V 4 O 10 + [ 17 ] and Re 2 O 7 + [ 18 ]. In addition to metal ions and their oxides, studies have shown that metal carbides can also activate methane, such as FeC 6 − [ 19 ], Mo 2 C 2 − [ 20 ], Ta 2 C 4 − [ 21 ], FeC 3 − [ 6 ], AuC + [ 22 ], FeC 4 + [ 23 ] and M C + [ 7 ]. These studies have explored some possible mechanisms for the activation of methane by metal carbide clusters.…”

“…These studies have explored some possible mechanisms for the activation of methane by metal carbide clusters. For example, the study of AuC + reveals a special hydride-transfer mechanism (HT) [ 22 ], while the study of FeC 3 - shows that methane and atomic clusters generate CC-coupling reaction products at high temperatures and explained the possible mechanism of non-oxidized methane aromatization at the molecular level [ 6 ]. The study of FeC 4 + shows that the cluster can activate the C–H bonds of methane via the hydrogen-atom transfer (HAT) mechanism at ambient temperature; the study used the frontier orbital theory to explain the root cause of the HAT reaction [ 23 ].…”

Mechanistic insights into the C–H activation of methane mediated by the unsupported and silica-supported VO2OH and CrOOH: a DFT study

“…20 Interestingly, the adsorbed oxygen species on metal surfaces were demonstrated to exhibit promotional or inhibitory effects, which depends strongly on the nature of metals. [21][22][23][24][25][26] In more recent years, a series of mechanistic scenarios were explored by Schwarz et al, [13][14][15][16][27][28][29] in which the classical hydrogen-atom transfer (HAT), 27 protoncoupled electron transfer (PCET), 28 and hydride transfer (HT) 29 pathways were explored and distinguished in various reaction systems for methane C-H activation.…”

Geometric and Electronic Structures of VB40/+ Clusters and Reactivity of the Cationic Cluster with Methane from Quantum Chemical Calculations

“…7−15 In the cases of transition metal carbide clusters, it was found that the center for activation of C−H bonds of methane can be either the transition metal 16,17 or the carbon atoms. 18,19 Also, reactivity of vanadium-doped rhodium clusters toward C−H activation were investigated with density functional theory. 14 The results showed that, as compared to the pure rhodium clusters, the monovanadiumdoped rhodium clusters have higher reactivity toward C−H activation.…”