1. Univ Lyon, CNRS, ENS Lyon, UCBL, Université de Lyon, CRMN UMR 5280, 69100 Villeurbanne, France.
2. National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Dr, Tallahassee, FL 32310, USA.
3. Swedish NMR Center, University of Gothenburg, Gothenburg, Sweden.
4. Department of Chemistry, Crown Street, University of Liverpool, Liverpool L69 7ZD, UK.