Two New Macropolyhedral Chalcogenaboranes: S2B16H18 and SeB16H18

The dithiaborane S2B16H18 (1) is a minor product isolated from the preparation of S2B17H17. It is structurally closely related both to the known compound iso-S2B16H16 (3) and to the new macropolyhedral selenaborarane SeB16H18 (2), which is isolated from the thermal decomposition of the [SeB18H19]− anion. Both new compounds 1 and 2 are therefore produced by boron loss from higher chalcogenaborane compounds. The single-crystal X-ray structures and the boron-11 NMR shielding characteristics show the close similarities of all three compounds.