1. Department of Chemistry, The University of Akron, Akron, Ohio 44325-3601, Department of Chemistry, 137 Sterling Chemistry Laboratory, Yale University, New Haven, Connecticut 06520-8107, and Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, m/c 0358, Urey Hall 5128, La Jolla, California 92093-0358