Synthesis, Crystal Structure, and Thermolysis of the First Tetracoordinate 1λ⁴,2-Selenazetidines:  Aziridine Formation Reaction from a Four-Membered Heterocycle Bearing Highly Coordinate Selenium

[structure: see text]. The first tetracoordinate 1lambda4,2-selenazetidines were synthesized by taking advantage of the Martin ligand and characterized by X-ray crystallographic analysis. The selenazetidines gave the corresponding aziridine and the cyclic selenenate on their thermolysis, which indicates the possibility that a highly coordinate 1,2-heterachalcogenetane may provide the corresponding heteracyclopropane regardless of the heteroatoms.