DFT studies for activation of C–H bond in methane by gas-phase (n =1−3).

Highlights: [•] We studied the gas-phase activation of methane by (n =1−3). [•] There is only one crossing point (CP) and minimum energy crossing point (MECP) on the three system, respectively. [•] The active center in the reaction of with methane include only one metal atom. [•] The product of with methane is hydrogen-bridge bond molecule. [•] For (n =1−3) with the increase of the metal atoms, the activation of methane C–H bonds rise sharply. [Copyright &y& Elsevier]