1. Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973, United States
2. Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, United States
3. Facultad de Ciencias, Universidad Central de Venezuela, Caracas 1020-A, Venezuela
4. Zoneca-CENEX, R&D Laboratories, Alta Vista, 64770 Monterrey Mexico