Nd3N2SeBr: Ein neues Nitridselenidbromid des Neodyms mit $\rm ^{1}_{\infty}\{[N_{2}Nd_{3}]^{3+}\}$‐Strängen aus hochkondensierten [NNd4]9+‐Tetraedern

Abstract

AbstractNd3N2SeBr: A New Nitride Selenide Bromide of Neodymium with $\rm ^{1}_{\infty}\{[N_{2}Nd_{3}]^{3+}\}$ Strands of Highly Condensed [NNd4]9+ TetrahedraThe oxidation of neodymium powder with selenium and sodium azide (NaN3) in the presence of neodymium tribromide (NdBr3) yields neodymium nitride selenide bromide with the composition Nd3N2SeBr when appropriate molar ratios of the reactants are used. Additional sodium bromide (NaBr) as a flux secures fast reactions (7 d) at 900 °C in evacuated silica tubes as well as the formation of dark brown single crystals. The orthorhombic crystal structure (Pnma, Z = 4) was determined from single crystal X‐ray diffraction data (a = 1288.13(9), b = 405.22(3), c = 1206.29(8) pm). There are three crystallographically different Nd3+ cations present. Nd1 resides in eightfold coordination of four N3−, two Se2− and two Br− anions forming a square antiprism and Nd2 is coordinated by three N3−, one Se2− and three Br− in the shape of a monocapped trigonal prism. Finally, an octahedral coordination sphere of one N3−, three Se2− and two Br− anions surrounds Nd3. However, the main feature in the crystal structure comprises N3−‐centred (Nd3+)4 tetrahedra arranged as chains $\rm ^{1}_{\infty}\{[NNd_{2}]^{3+}\}$ of cis‐edge connected [NNd4]9+ units first, which are further connected via two more edges to form strands $\rm ^{1}_{\infty}\{[N_{2}Nd_{3}]^{3+}\}$ of highly condensed all‐cisoid oriented [NNd4]9+ tetrahedra. They get bundled along [010] like a hexagonal rod packing and are held together by two radiographically indistinguishable Se2− and Br− anions, which thereby also achieve the charge balance.