1. Solid State and Structural Chemistry Unit, Indian Institute of Science, C. V. Raman Avenue, 560012 Bangalore (India)
2. Deptartment of Chemistry, Yale University, New Haven, CT 06520‐8107 (USA)
3. Lehrstuhl für Organische Chemie II, Ruhr‐Universität Bochum, D‐44801 Bochum (Germany)