1. Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-3706, and ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801