The isolation of BE2 heterocycles (E = Te, Se, S) from the reaction of a manganese borylene complex with elemental chalcogens is reported. The BTe2 and BSe2 cycles-a boraditellurirane and a boradiselenirane, respectively-are the first analogs of dioxiranes based on heavy chalcogens. While the BTe2 unit is still found datively bound to manganese, the Se and S analogs were isolated in their free forms. All heterocycles have been shown to transfer a chalcogen atom, allowing for the isolation of novel borachalcones and their dimerization products.