New mixed alkaline-earth nitridomolybdate(vi) nitride oxides with anion-ordered sub-structures

Abstract

New molybdenum(VI) nitride oxides were synthesised by the reaction of strontium nitride and calcium nitride with molybdenum foil at high temperature in sealed stainless steel crucibles. The reactions yielded single crystalline products determined by X-ray diffraction to form complex structures in the triclinic space group P (no. 2). The mixed alkaline earth compounds with composition Ca₃₈Sr₁₃[MoN₄]₁₂N₈O₃ and Ca₃₆Sr₁₅[MoN₄]₁₂N₈O₃ are isostructural with the quaternary nitride oxides Sr₅₁[WN₄]₁₂N₈O₃ and Ca₅₁[WN₄]₁₂N₈O₃. The structures contain isolated [MoN₄]⁶⁻ tetrahedra, partially disordered alkaline earth cations and an ordered sublattice of N³⁻ and O²⁻ anions. Oxide anions are coordinated only to the alkaline earth metals. The title compounds are the first mixed alkaline earth metal nitride oxides.