Stabilization of Unusual Oxidation and Coordination States by the Ligands OSF 5 , OSeF 5 , and OTeF 5

Compounds with the ligands OSF 5 , OSeF 5 , and OTeF 5 are now known for most of the chemical elements. The ability of these ligands to stabilize the highest valency levels of the central atoms to which they are bound is unsurpassed by any other polyatomic ligand. Examples are Xe(OTeF 5 ) 6 , Te(OTeF 5 ) 6 , W(OTeF 5 ) 6 , and U(OTeF 5 ) 6 or I(OTeF 5 ) 5 and Br(OSeF 5 ) 3 . Because of the ligands' size and internal bonding they hardly ever form bridges, and in this respect they differ from fluorine, although they do share the latter's high electronegativity.