Cyclic meso-ionic compounds. Part 19. The reaction of 5-ethoxy-1,2,3,4-tetrazolium and 5-ethoxy-1,2,3,4-thiatriazolium tetrafluoroborates with nucleophiles. The preparation of 1,2,3,4-tetrazolium- and 1,2,3,4-thiatriazolium-5-dicyanomethylides

Abstract

The reaction of 5-ethoxy-1,2,3,4-tetrazolium (4) and 5-ethoxy-1,2,3,4-thiatriazolium tetrafluoroborates (6) with malononitrile and triethylamine gives the meso-ionic 1,2,3,4-tetrazolium- and 1,2,3,4-thiatriazolium-5-dicyanomethylides (5) and (7) which are new classes of meso-ionic heterocycle. The meso-ionic 1,2,3,4-tetrazoles (8) and (9) form 1,2,3,4-tetrazolium tetrafluoroborates which react with aqueous sodium sulphide giving the formazans (11) and (13).