title: Theoretical study on the excess electron binding mechanism in the [CH(3)NO(2).(H(2)O)(n)](-) (n = 1-6) anion clusters.
abstract: The excess electron binding mechanism of the anionic nitromethane-water clusters was theoretically investigated using the potential energy surfaces calculated by high-level electronic structure theories. The mechanism was first studied for the dipole-bound and valence-bound anionic states of the CH(3)NO(2)(-) monomer with the ab initio multireference configuration interaction method to reveal the electron transformation process between these anionic states in detail. As a result, it was found that both the NO(2) tilting angle and NO distances play an essential role in this electron transformation. Following this result, various water solvation structures of the valence-bound CH(3)NO(2)(-) anion were optimized with up to six water solvents using the second-order Møller-Plesset (MP2) method. The calculated results predicted that the vertical detachment energy of the valence-bound CH(3)NO(2)(-) anion increases gradually with the hydration number, as is consistent with recent experimental observations. We also investigated metastable complexes composed of CH(3)NO(2) and (H(2)O)(6)(-) by using the MP2 and long-range corrected density functional theory calculations. Two types of dipole-bound forms were obtained for the [CH(3)NO(2).(H(2)O)(6)] anion complex. In one form the excess electron is internally suspended between the two moieties while in the other form two dipolar moieties are cooperatively arranged to reinforce the electron-dipole interaction.
authors.affiliation: Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570, Japan.
authors.forename: Haruki
authors.initials: H
authors.lastname: Motegi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Takayanagi
authors.forename: Takao
authors.initials: T
authors.lastname: Tsuneda
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yagi
authors.forename: Ryuzo
authors.initials: R
authors.lastname: Nakanishi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nagata