Monatshefte für Chemie - Chemical Monthly

, Volume 124, Issue 4, pp 381–389 | Cite as

Comparison of the crystal structures of Co2(X2O7)·2H2O,X=P and As

  • H. Effenberger
  • F. Pertlik
Anorganische Und Physikalische Chemie


Crystals of Co2(X2O7)·2H2O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, β=94.77(2)/94.74(2)°, space group P21/n,R=0.032/0.046,Rw=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO4 tetrahedra connected via a common corner to anX2O7 group the average 〈P-O〉 bond lengths are approximately equal (1.540 and 1.543 Å), but 〈As-O〉 differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio 〈Me-O〉/〈X-O〉 and the angle O-X-O.


Co2(P2O7)·2H2Co2(As2O7)·2H2Pyrophosphate Pyroarsenate Co(II)O6 octahedron 

Vergleich der Kristallstrukturen von Co2(X2O7)·2H2O,X=P und As


Kristalle von Co2(X2O7)·2H2O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, β=94.77(2)/97.74(2)°, Raumgruppe P21/n,R=0.032/0.046,Rw=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX2O7-Gruppen verknüpftenXO4-Tetraedern sind die mittleren 〈P-O〉-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert 〈As-O〉 signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten 〈Me-O〉/〈X-O〉 und dem WinkelX-O-X.


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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • H. Effenberger
    • 1
  • F. Pertlik
    • 1
  1. 1.Institut für Mineralogie und KristallographieUniversität WienWienAustria

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