1. Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Institut für Organische and Biomolekulare Chemie der Georg-August-Universität, Göttingen, Tammannstrasse 2, 37077 Göettingen, Germany, NIST Center for Neutron Research, Gaithersburg, Maryland 20899-6102, Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, and Department of Chemistry, University of North Texas, Denton, Texas 76203