1. Contribution from the Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1, Department of Chemistry and Biochemistry, Concordia University, 1455 De Maisonneuve Blvd Ouest, Montréal, Québec, Canada H3G 1M8, and Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6