Hexahalodiborate Dianions: A New Family of Binary Boron Halides

The electron‐precise binary boron subhalide species [B 2 X 6 ] 2− X=F, Br, I) were synthesized and their structures confirmed by X‐ray crystallography. The existence of the previously claimed [B 2 Cl 6 ] 2− , which had been questioned, was also confirmed by X‐ray crystallography. The dianions are isoelectronic to hexahaloethanes, are subhalide analogues of the well‐known tetrahaloborate anions (BX 4 − ), and are rare examples of molecular electron‐precise binary boron species beyond B 2 X 4 , BX 3 , and [BX 4 ] − .