1. Coordination Chemistry and Inorganic Pharmaceuticals Unit, Department of Pure and Industrial Chemistry; University of Nigeria; Nsukka 410001 Nigeria
2. Computational Chemistry Group, Department of Chemistry, Faculty of Science; University of Mauritius; Réduit 80837 Mauritius
3. Department of Applied Chemistry; University of Johannesburg; Doornfontein Johannesburg 2028 South Africa
4. Department of Chemistry; University of Johannesburg; PO Box 524, Auckland Park Johannesburg 2006 South Africa
5. Department of Chemical and Process Engineering; Jubail Industrial College; Jubail 31961 Saudi Arabia
6. Technische Universität; Otto Hahn Street 6, Lehrstühle für Anorganische Chemie II, Raum C2-07-332 Dortmund D-44227 Germany