1. Kobe Fundamental Research Laboratory, Sumitomo Bakelite Co., Ltd., 1-5, Murotani 1-chome, Nishi-ku, Kobe 651-2241, Japan; Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan; and Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu 611-0011, Japan