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Lanthanides: Divalent Solid Halides

  1. Gerd Meyer

Published Online: 17 DEC 2012

DOI: 10.1002/9781119951438.eibc2019

Encyclopedia of Inorganic and Bioinorganic Chemistry

Encyclopedia of Inorganic and Bioinorganic Chemistry

How to Cite

Meyer, G. 2012. Lanthanides: Divalent Solid Halides. Encyclopedia of Inorganic and Bioinorganic Chemistry. .

Author Information

  1. Universität zu Köln, Köln, Germany

Publication History

  1. Published Online: 17 DEC 2012

Abstract

Divalent rare earth metals (Sc, Y, and the lanthanides) are known in halides almost throughout the whole series. Two classes may be distinguished: RX2 = (R2+)(X)2 type dihalides, in which R2+ has the electronic configuration [Xe]6s05d04fn. Their structural behavior parallels that of the heavier alkaline-earth metal halides; for example, EuBr2 and SrBr2 are isostructural. All of these class I compounds are insulators. In the second class, R2+ has the electronic configuration [Xe]6s05d14fn−1; the occupation of a 5d state leads to (semi)metallic behavior. Their crystal structures resemble those of intermetallic phases, for example, LaI2 crystallizes with the CuTi2 type of structure. This class of dihalides RX2 is often written as (R3+)(e)(X)2. Except for the binary dihalides, there are a number of ternary halides, for example, CsTmCl3 and the mixed-valent K5Dy3I12 (class I), as well as BaLaI4 (class II). Oxide-halides with divalent lanthanides are also known, for example, {OSm4}I6 or the mixed-valent Eu2O2Br.

Keywords:

  • divalent;
  • electronic configuration;
  • halides;
  • crystal structures;
  • crystal orbital Hamiltonian population;
  • fermi level