A Direct Route to closo‐SBnCln Thiaboranes from Simple Electron‐Precise Synthons: The Different Role of Chalcogen Bonding in SB5Cl5 and SB11Cl11 Crystals

Abstract Six‐vertex closo ‐SB 5 Cl 5 ( 1 ) and ten‐vertex closo ‐1‐SB 9 Cl 9 ( 2 ) thiaboranes have been prepared, besides the already known 12‐vertex closo ‐SB 11 Cl 11 ( 3 ), from the co‐pyrolysis reaction of B 2 Cl 4 with S 2 Cl 2 at 280 °C in vacuo . The compounds are sublimable, off‐white solids. Their elemental composition has been determined by high‐resolution mass spectrometry. They were further characterized by one‐ and two‐dimensional 11 B NMR spectroscopy and X‐ray structure determination for 1 and 3 . Ab initio /GIAO/NMR computations support octahedral, bicapped square‐antiprismatic, and icosahedral geometries for 1 , 2 and 3 , respectively, as expected based on their closo ‐electron counts. 1 is the first isolated example of a neutral polyhedral closo ‐thiaborane with a cluster size smaller than ten vertices. The solid‐state structure of 3 is one of the rare examples of a single‐crystal X‐ray structure determination of an icosahedral heteroborane reported. The corresponding crystal‐packing forces show the different role of chalcogen bonding in these octahedral and icosahedral crystals. In addition, there is a mass‐spectrometry evidence for the recurrent formation of further thiaborane homologs of closo ‐SB n Cl n with n =4, 6, 10, and supra‐icosahedral 12.