Tris(diethylamino)cyclotriboran sowie Konstitutionsisomerie zwischen cyclo ;‐ und closo ‐Hexakis(diethylamino)hexaboran(6)

Tris(diethylamino)cyclotriborane and Constitutional Isomerism Between cyclo ;‐ and closo ‐Hexakis(diethylamino)hexaborane(6) The reaction of Et 2 NBCl 2 with potassium in boiling cyclohexane provides a mixture of aminopolyboranes, containing 20–25 mol‐% (BNEt 2 ) 3 ( 1 ), (BNEt 2 ) 4 ( 2 ), and cyclo ;‐(BNEt 2 ) 6 ( 3 ), respectively, as well as varying amounts of closo ;‐(BNEt 2 ) 6 ( 4 ). Whereas 1 and 3 have been highly enriched by means of HPLC, 4 has been isolated by column chromatography and crystallization. On standing in solution at room temperature, the cyclo ‐isomer 3 slowly rearranges to the closo ‐isomer 4 , while at elevated temperatures the reverse conversion occurs. Hence 4 , which is the first neutral B 6 compound with octahedral structure, has a relatively higher thermodynamic stability at normal conditions.