Affiliation: | 1. Institute of Organic Chemistry, University of Heidelberg, Im Neuenheimer Feld 270, 69120 Heidelberg (Germany), Fax: (+49)?6221‐544205;2. Institut of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany), Fax: (+49)?711‐6856‐4443 |