Condensed heterocycles Communication 43. Synthesis and transformations of benzo[b]selenopheno[3,2-d]-1,2,3-selenadiazoles and benzo[b]selenopheno[3,2-d]-l,2,3-thiadiazoles and a study of the molecular and crystal structure of dibenzo[b]selenopheno-[2,3-b;2,3-e]-1,4-diselenine

Abstract

1. Methods were developed for the synthesis of benzo[b]selenopheno[3,2-d]-1,2,3-thiadiazole and benzo[b]selenopheno[3,2-d]selenadiazole based on the reaction of the semicarbazone of 3-oxo-2,3-dihydrobenzo[b]selenophene with SOCl2 or SeO2, respectively. 2. The reaction of the selenadiazole with alcoholic alkali or the thermal decomposition of this compound gave dibenzo[2,3-b;2,3-e]-1,4-diselenine. 3. The major fragmentation processes of the M+. ions of the thiadiazoles and selenadiazoles upon electron impact is the consecutive loss of N2 and CS or CSe molecules, while in the case of the diselenine, the major process is the elimination of the heteroatoms. 4. A study was carried out on the crystal and molecular structure of dibenzo[b]selenopheno[2,3-g;2,3-e]-1,4-diselenine which revealed that this compound has trans configuration and twist boat conformation of the central heterocycle.