Se₂NBr₃, Se₂NCl₅, Se ₂NCl₆^-: New nitride halides of selenium(III) and selenium(IV)

Se₂NBr₃, a planar molecule shaped liked dividers, was formed by the reaction of SeBr₄ with N(SiMe₃) ₃, which reduced the selenium to the trivalent state. Under the same conditions, Se₂NCl₅ was obtained by the reaction of SeCl₄ with N(SiMe₃)₃, retaining the tetravalent state of selenium. The molecule is formed by two edge-sharing pseudotrigonal bipyramids with selenium as their central atoms. Se₂NCl₅ reacts with PPh₄Cl to form the Se₂NCl₆ ^- ion by the addition of a Cl^- ion to only one of the two selenium atoms, resulting in pseudooctahedral coordination of this atom. Ab initio calculations for all the compounds reported confirm the experimentally determined structures.