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Z. Naturforsch. 2014,
69b, 580 – 588
doi:10.5560/ZNB.2014-4015
A Direct Synthesis of a Strongly Zwitterionic 6,6′-Diaminofulvalene
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
Supporting Material: