Das neue Neodym(III)‐Oxidchlorid‐Oxoselenat(IV) Nd7O5Cl3[SeO3]4

Abstract

AbstractPale violet, needle‐shaped single crystals of the new neodymium(III) oxide chloride oxoselenate(IV) Nd7O5Cl3[SeO3]4 were obtained by the reaction of Nd2O3 and NdCl3 with SeO2 (molar ratio: 3:1:4) in evacuated silica ampoules within seven days at 775 °C, if an excess of CsCl worked as fluxing agent. Nd7O5Cl3[SeO3]4 crystallizes in the triclinic space group P$\bar{1}$ with the lattice parameters a = 694.46(4), b = 944.53(5), c = 1567.92(9) pm, α = 87.821(3), β = 81.849(3), γ = 84.852(3)° and Z = 2. Its structure exhibits seven crystallographically different Nd3+ cations, of which (Nd1)3+ – (Nd4)3+ are coordinated by O2– anions forming distorted square prisms. The polyhedra of (Nd1)3+ and (Nd2)3+ receive additional caps by one Cl– anion each, and (Nd5)3+ – (Nd7)3+ show mixed square antiprismatic environments of O2– and Cl– anions too. However, the polyhedra of (Nd5)3+ and (Nd6)3+ include two, the polyhedron about (Nd7)3+ even three Cl– anions. Two‐dimensional ${}^2_\infty \{[\textrm{O}_5\textrm{Nd}_7]^{11+}\}$ layers of edge‐ and vertex‐linked [ONd4]10+ tetrahedra are built up by (O1)2– – (O5)2– together with all Nd3+ cations. All the other oxygen atoms belong to four crystallographically different Se4+ cations erecting ψ1‐tetrahedral oxoselenate(IV) units [SeO3]2– with stereochemically active non‐bonding electron pairs (“lone pairs”) pointing into the free space between the ${}^2_\infty \{[\textrm{O}_5\textrm{Nd}_7]^{11+}\}$ layers. Three independent Cl– anions in threefold coordination of Nd3+ cations interconnect the ${}^2_\infty \{([\textrm{O}_5\textrm{Nd}_7][\textrm{SeO}_3]_4)^{3+}\}$ layers to form a three‐dimensional network, thereby achieving the charge balance.