Institute of Bio- and Nanosystems (IBN3) and Center of Nanoelectronic Systems for Information Technology (CNI), Research Center Jülich, D-52425 Jülich, Germany, Institute of Inorganic Chemistry, RWTH Aachen, D-52074 Aachen, Germany, and Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland (At 2007-11-01)