title: Solvation structure and stability of [(CH3)2NH]m(NH3)n-H hypervalent clusters: ionization potentials and switching of hydrogen-atom localized site.
abstract: Ionization potentials (IPs) of [(CH(3))(2)NH](m)(NH(3))(n)-H hypervalent radical clusters produced by an ArF excimer laser photolysis of dimethylamine (DMA)-ammonia mixed clusters are determined by the photoionization threshold measurements. The IPs of the DMA(1)(NH(3))(n)-H hypervalent radicals decrease rapidly with the number of ammonia up to n=4, and then its decrease rate becomes much slower for n ≥ 5. This trend is very similar to that found for NH(4)(NH(3))(n) clusters. The calculated results on the stable structures and IP as well as the observed IP for DMA(1)(NH(3))(n)-H indicate that the hydrogen atom-localized site is the NH(3) moiety for n=1, while the doubly coordinated DMA-H is favorable for n=2-4, and then 4-fold-coordinated NH(4) is again more stable for n ≥ 5. These changes are consistent with the results on the femtosecond pump-probe experiments of DMA(n)-H clusters. Switching of the hydrogen atom-localized site is ascribed to the instability of DMA-H against a hydrogen-atom dissociation.
authors: Department of Chemistry, Graduate School of Science, Fukuoka University, Fukuoka 814-0180, Japan.
authors: Yuji
authors: Y
authors: Yamada
authors: Haruki
authors: H
authors: Ishikawa
authors: Kiyokazu
authors: K
authors: Fuke