AbstractActivation of methane by oxidative addition and σ‐bond metathesis has been investigated for (N‐N)M(CH3) (M = Pd+, Pt+, Rh+, Ir+, Rh, Ir; N‐N = (HNCHCHNH) using different density functional approaches. The pathway of oxidative addition is in general favored, the exceptions being Pd+ and Rh+. Oxidative addition is clearly more favorable for the third‐row metal complexes than those of the second row. The third‐row metal complexes also tend to have a lower activation barrier for σ‐bond metathesis than those of the second row. In each case, the oxidative addition is preceded by formation of a sigma complex. The bonding energies of these complexes are significantly stronger for the cationic systems. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003