The Non-Isotypical Nitride Selenides Dy3NSe3 and Ho3NSe3: Chains and Dimers

Falk Lissner (1) , Thomas Schleid (1)

1 Universitaet Stuttgart

The non-isotypical lanthanoid(III) nitride selenides M3NSe3 of dysprosium (Dy3NSe3) and holmium (Ho3NSe3) are formed by the reaction of the respective rare-earth metal (M = Dy and Ho) with sodium azide (NaN3), selenium and an excess of iodine at 900 °C from torch-sealed evacuated silica ampoules within seven days. Dy3NSe3 crystallizes orthorhombically (a = 1245.38(9), b = 393.69(3), c = 1303.74(9) pm) in space group Pnma with Z = 4, whereas monoclinic Ho3NSe3 (a = 1152.93(8), b = 1006.61(7), c = 1248.76(9) pm, β = 112.847(3)°) adopts the space group C2/c with Z = 8. Both crystal structures comprise three crystallographically different M3+ cations along with one N3– and three independent Se2– anions, but they differ fundamentally in the linkage of their structure dominating N3–-centered (M3+)4 tetrahedra. In Dy3NSe3, these [NDy4]9+ units are vertex-linked to form {[N(Dy1) (Dy2) (Dy3) ]6+} chains (t = terminal, v = vertex-shared), while just two [NHo4]9+ tetrahedra have one edge in common to join as isolated bitetrahedra {([N(Ho1) (Ho2) (Ho3) ]6+)2} (e = edge-connecting, t = terminal) in Ho3NSe3. So the alternative formula Ho6N2Se6 with Z = 4 is likewisely valid. The M3+ cations in Dy3NSe3 show coordination numbers of six, six plus one and seven, whereas in the case of Ho3NSe3 only coordination numbers of six occur with respect to the anions (N3– and Se2–). In both crystal structures the three independent sorts of Se2– anions provide the three-dimensional linkage as well as the charge balance of the {[NDy3]6+} chains and the {[N2Ho6]12+}

Mots clés: Physical Sciences

Falk Lissner, Thomas Schleid. The Non-Isotypical Nitride Selenides Dy3NSe3 and Ho3NSe3: Chains and Dimers. Journal of Inorganic and General Chemistry / Zeitschrift für anorganische und allgemeine Chemie, 2009, 635 (6-7), pp.815. ⟨10.1002/zaac.200900005⟩. ⟨hal-00484128⟩