SYNTHESIS, PROPERTIES, AND METALLIC CATION-RADICAL SALTS OF A NEW CLASS OF ELECTRON PI-DONORS - 2,7-DISUBSTITUTED NAPHTHO[1,8-DE-5,4-D'E']BIS[1,3]THIAZINES

The first 2,7-disubstituted naphtho[1,8-de:5,4-d'e']bis[1,3]thiazines have been prepared from 4,8-dibromo-1,5-diaminonaphthalene, in two ste ps, via intramolecular nucleophilic substitution. They are shown to be two-stage, electron pi-donors and form highly conducting cation radic al (CR) salts with I-3-, IBr2-, and PF6- as counterions. Noteworthy is the IBr2- salt of ethylthio)naphtho[1,8-de:5,4-d'e']bis[1,3]thiazine ((10a)(IBr2)(0.46)), which crystallizes in the triclinic system, space group P1, a = 4.226(1) Angstrom, b = 8.6877(1) Angstrom, c = 11.481(2 ) Angstrom>, alpha = 105.30(1)degrees, beta = 90.94(1)degrees, gamma = 100.13(1)degrees, Z = 1. It shows a room temperature conductivity of sigma(RT) = 250 S/cm and exhibits metallic behavior down to 125 K. All of the CR salts reported here have very similar crystal structures ty pical of segregated stacking. Several S- -S but also interestingly C- -C intermolecular contacts have been observed.