1. Contribution from the Department of Chemistry, Center for Metals in Biocatalysis, and Supercomputer Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, Minnesota 55455, the Department of Chemistry, North Dakota State University, P.O. Box 5516, Fargo, North Dakota 58105, and the Department of Applied Chemistry, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565, Japan