Z. Naturforsch. 2014, 69b, 580 – 588
A Direct Synthesis of a Strongly Zwitterionic 6,6′-Diaminofulvalene
Dominic Schmid, Alexander Seyboldt and Doris Kunz
Institut für Anorganische Chemie, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 18, 72076 Tübingen, Germany
Reprint requests to Prof. Dr. Doris Kunz. Fax: +49 7071 29-2436. E-mail: Doris.Kunz@uni-tuebingen.de
Received January 31, 2014 / published online May 7, 2014
Upon reaction of the dipyrido-anellated guanidinium salt 1 with one equivalent of CpNa we were able to synthesize the dipyrido-anellated diaminofulvalene 4 in one step in 33 % isolated yield. This shortens the initial route that applies a literature-known fulvalene synthesis via uronium salt 3 by two steps and avoids the need for a sacrificial equivalent of CpNa. Although the X-ray structure analysis reveals a shorter exocyclic double bond than observed in the diaminofulvalene V, a theoretical analysis based upon DFT calculations shows a stronger zwitterionic character for the dipyridofulvalene 4.
Key words: Fulvene, Fulvalene, Imidazolium Salt, Guanidinium Salt, DFT
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