Dicyanomethylenephenoxazines and dicyanoiminophenoxazines as novel donor-acceptor systems

5 Dicyanomethylenephenoxazines and dicyanoiminophenoxazines as novel donor-acceptor systems 

71-System molecules exhibiting planarity in the neutral or radical cation form have gained new interest as precursors for organic metals. In this regard, substituted derivatives of thianthrenes 86 [166], 

Phenothiazines are known to give rise to stable radical cations and dications [171-173] as well as to charge-transfer complexes. Phenothiazinyl-substituted ligands have been used in metal complexes to study electron-transfer processes [174-176]. Recently, Gompper and co-workers have reported the 1-phe-nothiazinyl-vinamidinium salt as a model for a molecular switch [177]. 

The presence of the methyl group attached to the nitrogen atom was necessary in order to increase the solubility and so facilitate the subsequent reaction of the quinone 91 to form the TCNQ or DCNQl derivatives. 

The reaction of quinone 91 with malononitrile and TiCl4 in the presence of pyridine led to the TCNQ derivative 92 in moderate yield. The DCNQl derivative 94 was prepared by reaction of quinone 91 with bis(trimethylsilyl)carbodiimide (BTC) in the presence 

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