The performance of density-functional/Hartree–Fock hybrid methods: Cationic transition-metal methyl complexes MCH+3 (M=Sc–Cu,La,Hf–Au)

Hybrid methods, including a mixture of Hartree–Fock exchange and density functional exchange-correlation treatment have been applied to the cationic methyl complexes MCH+3 of the first and third-row transition metals (M=Sc–Cu,La,Hf–Au). Bond dissociation energies and optimum geometries obtained with the ‘‘Becke-Half-and-Half-Lee–Yang–Parr’’ and ‘‘Becke-3-Lee–Yang–Parr’’ functionals and from calibration calculations employing quadratic configuration interaction with single and double excitations and with a perturbative estimate of triple excitations are reported. A comparison of the results for the 3d-block species to earlier high-level ab initio calculations and experimental data is carried out in order to assess the reliability of hybrid methods as a practical tool in organometallic chemistry. Furthermore, the bond dissociation energies of the cationic 5d-block transition-metal methyl complexes, many of which have not been investigated so far, are predicted.