1. Department
of Chemistry, Inorganic Section, Jadavpur University, Kolkata 700 032, India
2. Department
of Physics, Jadavpur University, Kolkata 700032, India
3. Departamento
de Química Inorgánica, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria, 28040 Madrid, Spain
4. School
of Chemistry, The University of Reading, P.O. Box 224, Whiteknights, Reading RG6 6AD, U.K.