COMPARATIVE ELECTRONIC ANALYSIS BETWEEN HYDROGEN TRANSFERS IN THE CH4CH3+, CH4/CH3-CENTER-DOT AND CH4/CH3- SYSTEMS - ON THE ELECTRONIC NATURE OF THE HYDROGEN (H-, H-CENTER-DOT, AND H+) BEING TRANSFERRED/

A comparative electronic analysis of the generally termed hydrogen tra nsfers between CH4 and the CH3+, CH3., and CH3- fragments is presented . These systems are taken as simple models of hydride (H-), hydrogen ( H-.), and proton (H+) transfers between two carbon fragments (in these simple cases being modelized by two CH3+, CH3., and CH3- fragments, r espectively). The study is mainly focused on analysis of the electroni c nature of the type of hydrogen being transferred in each system, and for this reason a topological analysis of charge density distribution s was performed. Computation of Bader atomic charges and construction of the charge density, gradient vector field, and Laplacian of the cha rge density maps reveal the specific features of the electronic nature of the transferring H-, H-., and H+. Moreover, characterization of th e bond critical points on the charge density surface permits clarifica tion of the differences in atomic interactions between H-, H-., and H and the carbon belonging to each CH3+, CH3., and CH3- fragment, respe ctively. A charge density redistribution analysis is also performed to quantify the reorganization of the electron density when going from t he reactant complex to the transition state. Finally, effects of inclu sion of the correlation energy at the MP2 and CISD levels are also dis cussed.