1. Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany
2. Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056 Aachen, Germany, and Poncelet Laboratory, Independent University of Moscow, Moscow Center for Continuous Mathematical Education, Bolshoi Vlasevsky Per. 11, 119002 Moscow, Russia