Experimental and theoretical studies of Hf*, Ta+, and Ta2+ reacting with methane

Guided-ion-beam tandem mass spectrometer techniques are used to study the activation of methane by the third-row transition metal ions, M = Hf, Ta+ , and Ta2 + . In the studies of the third-row transition metals reacting with methane, experimental cross sections are measured as a function of kinetic energy of the reactants and are used to derive the absolute bond dissociation energies of the transition metal complexes, MCHX + (x = 0-3). In addition, TaCfi2+ is reacted with H2 and D2 to examine the rate constants for the reverse reaction. Complementary ab initio calculations are performed to provide the electronic structures of the product species, as well as intermediates and transition states along the reactive potential energy surface. The main goal of this work is to better understand the ability of atomic transition metal ions to activate C-H bonds as well as provide fundamental information regarding metal-ligand bond interactions and provide insight into the role of spin conservation in these heavy-metal systems.