1. Chemistry Department University of Pretoria Private X20 Hatfield 0028 South Africa
2. Molecular Sciences Institute School of Chemistry University of the Witwatersrand Johannesburg 2050 South Africa
3. Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
4. Departamento de Química Orgánica I Centro de Innovación en Química Avanzado (ORFEO-CINQA) and Facultad de Ciencias Químicas Universidad Complutense de Madrid 28040 Madrid Spain
5. Laboratory of Inorganic Chemistry, Environmental and Chemical Engineering University of Oulu P. O. Box 3000 90014 Oulu Finland