[CuEn 3]MoO4: Synthesis, Structure, Jahn-Teller Effect, Transformations in the Range 100–1263 K

S. P. Khranenko, A. S. Sukhikh, R. E. Nikolaev, S. A. Gromilov

Research output: Contribution to journalArticlepeer-review

Abstract

The crystal structure of [CuEn3]MoO4 (En is ethylenediamine) is studied in a range 100–390 K. The crystallographic data at 100 K are as follows: a = 27.5808(9) Å, c = 9.9043(4) Å, space group P3 ¯ , V = 6524.8(4) Å3, Z = 18. The coordination of copper atoms is a distorted square bipyramid. In three crystallographically independent cations. four short Cu-N distances are 2.041(2)–2.093(2) Å, two long ones in a trans position are 2.397(2)–2.496(2) Å (at 200 K these intervals are 2.039(4)–2.148(4) Å and 2.332(2)–2.461(4) Å respectively). In a range from 200 K to 298 K, the transition occurs to the space group P3 ¯ c1 (a = 15.9992(6) Å, c = 9.9385(4) Å, V = 2203.17(19) Å3, Z = 6) and the Cu-N distances are aligned: 2.086(6) Å, 2.162(7) Å, 2.273(8) Å. At 390 K the Jahn-Teller effect disappears and the Cu-N distances are 2.153(4) Å (a = 9.2785(14) Å, c = 10.0035(18) Å, P3 ¯ 1c, V = 745.8(3) Å3, Z = 2). It is shown that with increasing temperature from 100 K to 320 K the average Mo-O distances decrease from 1.766 Å to 1.699 Å. The ex situ powder X-ray diffraction study of the formation process of metal and carbide phases is performed during [CuEn3]MoO4 thermal decomposition in the He atmosphere in the presence of LiH. Starting from 973 K, a mixture of Mo2C and the fcc phase based on the Cu structure (a ≈ 3.65 Å) forms.

Original languageEnglish
Pages (from-to)267-273
Number of pages7
JournalJournal of Structural Chemistry
Volume61
Issue number2
DOIs
Publication statusPublished - 1 Feb 2020

Keywords

  • complex salt
  • copper tris-ethylenediamine
  • crystal chemistry
  • Jahn-Teller effect
  • molybdate anion
  • X-ray diffraction analysis
  • CRYSTAL-STRUCTURES
  • TRIS(ETHYLENEDIAMINE)ZINC(II) SULFATE
  • PROGRAM

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