Jump to main content
Jump to site search

Issue 40, 2017
Previous Article Next Article

A new glance on R2MGe6 (R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6 germanides

Author affiliations

Abstract

The R2PdGe6 series (R = rare earth metal) was structurally characterized, and the results achieved were extended for a comprehensive study on R2MGe6 (M = another metal) compounds, employing symmetry-based structural rationalization and energy calculations. Directly synthesized R2PdGe6 exists for almost all R-components (R = Y, La–Nd, Sm and Gd–Lu) and even if with La is probably metastable. Several single crystal X-ray analyses (R = Y, Ce, Pr, Nd, Er and Lu) indicated oS72-Ce2(Ga0.1Ge0.9)7 as the correct structure. The alternative In-flux method, once optimized, produced three good quality R2PdGe6 single crystals: La2PdGe6 and Pr2PdGe6 turned out to be mS36-La2AlGe6-type non-merohedrally twinned crystals and Yb2PdGe6 is of oS72-Ce2(Ga0.1Ge0.9)7-type. The vacancy ordering phenomenon was considered as a possible cause of the symmetry reduction relations connecting the most frequently reported 2 : 1 : 6 structural models (oS18, oS72 and mS36) with the oS20-SmNiGe3 aristotype. The detected twin formation is consistent with the symmetry relations, which are discussed even considering the validity of the different structural models. DFT total energy calculations were performed for R2PdGe6 (R = Y and La) in the three abovementioned structural models, and for La2MGe6 (M = Pt, Cu, Ag and Au) in the oS18 and oS72 modifications. The results indicate that the oS18-Ce2CuGe6 structure, prevalently proposed in the literature, is associated with the highest energy and thus it is not likely to be realized in these series. The oS72 and mS36 polytypes are energetically equivalent, and small changes in the synthetic conditions could easily stabilize any of them, in agreement with experimental results obtained by direct and flux syntheses.

Graphical abstract: A new glance on R2MGe6 (R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6 germanides

Back to tab navigation

Supplementary files

Publication details

The article was received on 23 Jul 2017, accepted on 18 Sep 2017 and first published on 18 Sep 2017


Article type: Paper
DOI: 10.1039/C7DT02686B
Citation: Dalton Trans., 2017,46, 14021-14033
  • Open access: Creative Commons BY-NC license
  •   Request permissions

    A new glance on R2MGe6 (R = rare earth metal, M = another metal) compounds. An experimental and theoretical study of R2PdGe6 germanides

    R. Freccero, P. Solokha, D. M. Proserpio, A. Saccone and S. De Negri, Dalton Trans., 2017, 46, 14021
    DOI: 10.1039/C7DT02686B

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

    Reproduced material should be attributed as follows:

    • For reproduction of material from NJC:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
    • For reproduction of material from PCCP:
      [Original citation] - Published by the PCCP Owner Societies.
    • For reproduction of material from PPS:
      [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
    • For reproduction of material from all other RSC journals:
      [Original citation] - Published by The Royal Society of Chemistry.

    Information about reproducing material from RSC articles with different licences is available on our Permission Requests page.

Search articles by author

Spotlight

Advertisements