1. Semenov-Institute of Chemical Physics, Russian Academy of Sciences, Moscow 117977 GSP1, Kosygin st. 4, Russia; High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan; Nesmeyanov-Institute of Organo-Element Compounds, Russian Academy of Sciences, Moscow 119991, Vavilov st. 28, Russia; and RCNT, University of Tokyo, JAERI, Tokai-Maru, Ibaraki 319-1106, Japan