1. Department of Chemistry, Dalhousie University, Halifax, Nova Scotia B3H 4J3, Canada, Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick E3B 6E2, Canada, X-ray Crystallography Laboratory, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada, and Department of Chemistry and Biochemistry, University of California, San Diego, 2040 Urey Hall Addition, 9500 Gilman Drive, MC 0332, La Jolla, California 92093-0332