Affiliation: | 1. Division of Organic Chemistry;2. Central NMR Facility, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411‐008 (India), Fax: (+91)?20‐25902629;3. Institute for Physical Chemistry, Tammannstrasse 6, 37077 G?ttingen (Germany), Fax: (+49)?551‐39‐3144 |