1. Chemistry Department, Faculty of Science, Minia University, El-Minia, Egypt
2. Institute of Organic Chemistry, Hagenring 30, TU Braunschweig, 38106 Braunschweig, Germany
3. Institute of Inorganic and Analytical Chemistry, Hagenring 30, TU Braunschweig, 38106 Braunschweig, Germany