Synthesis of new soluble triphenodithiazines and investigation of their donor properties

Abstract

The syntheses of 6 and ?, starting from 3,6-dichloro-2,5-bis(2-EPR measurements on the radical cations derived from 6 and thioanisido)-1,4-benzoquinone (4), are reported. The solid-state 7 both suggest a planarized conformation of these species. Oxiconformations of 6 and ? are elucidated by X-ray structure dation 01 6 with strong oxidants leads quantitatively to the analysis, and the cyclovoltammetric investigation of 6 and 7 quinoid triphenodithiazine 8, whereas the charge-transfer in solution shows low and reversible oxidation half-waves for complex formed between 7 and DDQ exhibits semiconducting both compounds. The relatively high oxidation potentials of properties. 7 compared to 6 are related to their conformational features.Triphenodithiazine 2 has recently attracted attention as a model compound for poly(phen0thiazine) (1)['-31. This ladder polymer is supposed to possess high intrinsic conductivity and shows non-linear optical activityL4-']. The two most important features of this system are the rigid ladder structure that allows for extended n-conjugation and the presence of heteroatoms, which should give rise to low oxidation potentials and high donor ability. 1 is a hetero analog of a ladder-type arylenemethideL8]. The parent compound 7,14-dihydrotriphenodithiazine (3) has been synthesized by starting from N,N'-diphenyl-p-phenylenediamine which is thionated with elemental sulfur and a trace of iodine at elevated temperatures in a high-boiling solventL2'. Unfortunately, the product shows a very low solubility, which seriously inhibits a full spectroscopic characterization and further chemical transformations. In order to obtain detailed information on the chemical and electrochemical properties of 7,14-dihydrotriphenodithiazine and triphenodithiazine, we have worked out a straightforward synthesis of a soluble derivative.