1. State University of New York at Binghamton, Department of Chemistry, P. O. Box 6000, Binghamton, NY 13902‐6000, USA, Fax: +1‐607‐777‐4865
2. University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, m/c 0358, LaJolla, CA 92093‐0332, USA