ChemInform Abstract: Framework Structures of Interconnected Layers in Calcium Iron Arsenides.

Abstract

Iron Arsenides. -The new compounds Ca n(n+1)/2(Fe1-x )(2+3n) As(n+1)(n+2)/2 (n = 1-3; M 1 : Nb, Pd, Pt; M 2 : , Pd, Pt) and (Ca,Na)3(Fe,Nb)8As6 are synthesized by solid state reaction of stoichiometric mixtures of the elements (alumina or Nb tubes, 900-1000 C) and their crystal structures are determined by single crystal XRD. In the compounds, iron arsenide tetrahedral layers are bridged by iron-centered pyramids, giving rise to so far unknown frameworks of interconnected FeAs layers. Channels within the structures are occupied by Ca and Pd resp. Pt. Common basic building blocks are identified and discussed. CaFe 5As3, Ca2.56Na0.44Fe7.49Nb0.51As6, Ca3Fe7.705Pt1.295As6, Ca6Fe7.88Pd6.12As10, and Ca 6Fe7.62Pt6.38As10 crystallize in the monoclinic space group P21/m with Z = 2. The compounds Ca 3Fe6.98Pd2.02As6, Ca3Fe6.72Pt2.28As6, and Ca3Fe4.74Pd4.26s6 crystallize in the orthorhombic space group Pnma with Z = 4. -(STUERZER, T.; HIEKE, C.; LOEHNERT, C.; NITSCHE, F.; STAHL, J.; MAAK, C.; POBEL, R.; JOHRENDT*, D.; Inorg. Chem. 53 (2014) 12, 6235-6240, http://dx.