1. Department of Chemistry and Biochemistry-0358, University of California at San Diego, La Jolla, California 92093-0358, Department of Chemistry, University of Delaware, Newark, Delaware 19716, Department of Chemistry, Northeastern University, Boston, Massachusetts 02115, Center for Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Tallahassee, Florida 32310, and Department of Chemistry, Indiana University, Bloomington, Indiana 47405.