Chalcogenation Reactions of Overcrowded Doubly Bonded Systems between Heavier Group 15 Elements

Novel heterocyclic compounds containing chalcogen (S, Se, and Te) and pnictogen (P, Sb, and Bi) atoms were obtained by chalcogenation reactions of the doubly bonded systems between heavier group 15 elements (dipnictenes) kinetically stabilized by 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) groups. Whereas the sulfurization reaction of BbtP=PBbt (1) with elemental sulfur (S8) gave the Bbt-substituted thiadiphosphirane, i.e., the three-membered ring compound of P–S–P, those of BbtSb=SbBbt (2) and BbtBi=BiBbt (3) afforded the corresponding five-membered ring compounds, i.e., the 1,2,4,3,5-trithiadistibolane and 1,2,4,3,5-trithiadibismolane, as the main products, respectively. From each selenization reaction of dipnictenes 1–3 using elemental selenium, the corresponding three-membered ring compounds (selenadipnictiranes) were obtained as stable compounds. On the other hand, the tellurization reactions of distibene 2 and dibismuthene 3 using (n-Bu)3P=Te gave the corresponding telluradipnictiranes as in the case of their selenization reactions, though diphosphene 1 underwent no tellurization when (n-Bu)3P=Te or elemental tellurium was used as a tellurium source.