Nonacarbene

Iwamura et al.[93 have reported the preparation of a branched-chain nonacarbene possessing a nonadecet ground state with the goal of constructing superparamagnetic polycarbenes. The preparation of three-directional, diradicals was reported by Bock et alJ94J and a tetrahedral, tetraradical has been synthesized by Kirste et al. The synthesis, characterization, and physical properties of the perchloro-2,6-bis(diphenylmethyl)-pyridine-a,a -ylene biradical have also been reported. 

Nakamura, N., Inoue, K. and Iwamura, H. (1993). A branched-chain nonacarbene with a nonadecet ground state a step nearer to superparamagnetic polycarbenes. Angew. Chem. Int. Ed. 32, 872-874... 

Non-Kekule structures are of importance for the design of organic ferromagnets. Having prepared a hexacarbene with a tridecet ground state [21] Iwamura and co-workers have now been able to obtain a branched nonacarbene, 25, which possesses the record number of 18 unpaired electrons [22]. 

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