1. Chemistry Department, Faculty of Science; Minia University; El-Minia 61519 Egypt
2. Department of Medicinal Chemistry, Faculty of Pharmacy; El-Minia University; 61519 El-Minia Egypt
3. Institute of Organic Chemistry; Karlsruhe Institute of Technology; Fritz-Haber-Weg 6 76131 Karlsruhe Germany
4. Laboratory of Inorganic Chemistry, Department of Chemistry; University of Helsinki; P.O. Box 55 (A. I. Virtasen aukio 1) 00014 Helsinki Finland