1. IMM, Solid State Chemistry, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands, IMM, High Field Magnet Laboratory HFML, Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands, and Crystal and Structural Chemistry, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands