1. Department of Chemistry and Center for Metals in Biocatalysis University of Minnesota Minneapolis MN 55455 USA
2. Current address: Department of Physical and Environmental Sciences Texas A & M University-Corpus Christi Corpus Christi TX 78412 USA
3. Molecular Inorganic Chemistry Stratingh Institute for Chemistry Faculty of Science and Engineering University of Groningen Nijenborgh 4 9747 AG Groningen The Netherlands
4. Chemical Theory Center and Minnesota Supercomputing Institute University of Minnesota Minneapolis MN 55455-0431 USA