1. Institute of Applied Physics, Moldova State University, Academiei 5, MD2028 Chisinau, R. Moldova
2. Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
3. Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland