Homogeneous Conversion of Methane to Methanol. 2. Catalytic Activation of Methane by cis- and trans-Platin: A Density Functional Study of the Shilov Type Reaction

摘要: The C-H activation of methane catalyzed by cis- and trans-platin in aqueous solution has been studied density functional based computational methods. By analogy with the Shilov reaction, initial step is replacement an ammonia ligand methane, followed formation a methyl complex elimination o proton. computations utilize B3LYP hybrid functionals, effective core potentials, double-{zeta} to polarized basis sets include solvation effects dielectric continuum method. In contrast reaction Seigbahn Crabtree (J.Am.Chem.Soc. 1996, 118, 4443), platins found be effectively rate determining, that energy barriers are comparable those substitution viz. {approximately} 34 44 kcal/mol for trans-platin, respectively. Several pathways subsequent proton were identified. For cis-platin associated oxidative addition {sigma}-bond metathesis type mechanisms comparable, while predicted strongly preferred over metathesis, which, interestingly, also proceeds through Pt(IV) hydrido as intermediate.more » line accepted ideas on trans influence, hydride ligands complexes arise reactions always cis each other. On population analyses it suggested Pt-H Pt-CH{sub 3} bonds best described covalent and, further, preference anions other consequence such bonding. light these findings, energies several bisulfate recalculated, CH{sub H places revised results provide evidence thermodynamic feasibility catalysts [Pt(NH{sub 3}){sub 2}(OSO{sub 3}H){sub 2}] or 3}H)(H{sub 2}SO{sub 4})]{sup +}.« less