1. Department
of Chemistry and Applied Biosciences, ETH Zürich, Vladimir
Prelog Weg 1-5, CH-8093 Zürich, Switzerland
2. Centre
de RMN à Très Hauts Champs, CRNS/ENS-Lyon/UCB Lyon 1, Université de Lyon, 5 rue de la Doua, 69100 Villeurbanne, France
3. Université de Toulouse and CNRS, LPCNO INSA/UPS/CNRS, 135 avenue de Rangueil, 31077 Toulouse Cedex 4, France
4. Chemical
Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
5. Department
of Chemistry, University of California, Berkeley, California 94720, United States