Zirconium(III) iodide
Ball-and-stick model of a polymer chain of face-sharing octahedra in the crystal structure of zirconium(III) iodide
Ball-and-stick model of the packing of polymer chains in the crystal structure of zirconium(III) iodide
Names
IUPAC name
Zirconium triiodide
Identifiers
3D model (JSmol)
  • InChI=1S/3HI.Zr/h3*1H;/q;;;+3/p-3
    Key: BPVKTQRLRAVYEX-UHFFFAOYSA-K
  • [Zr+3].[I-].[I-].[I-]
Properties
I3Zr
Molar mass 471.937 g·mol−1
Appearance dark blue crystals[1]
Melting point 727 °C (1,341 °F; 1,000 K)
Structure
Orthorhombic
Pmmn, No. 59
a = 12.594 Å, b = 6.679 Å, c = 7.292 Å
Related compounds
Other anions
 Zirconium(III) chloride
Zirconium(III) bromide
Other cations
 Titanium(III) iodide
Hafnium(III) iodide
Related compounds
 Zirconium(IV) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Zirconium(III) iodide is an inorganic compound with the formula ZrI3.

Preparation

Like other group 4 trihalides, zirconium(III) iodide can be prepared from zirconium(IV) iodide by high-temperature reduction with zirconium metal, although incomplete reaction and contamination of the product with excess metal often occurs.[2]

3 ZrI4 + Zr → 4 ZrI3

An alternative is to crystallise zirconium(III) iodide from a solution of zirconium(III) in aluminium triiodide. The solution is prepared by reducing a eutectic solution of ZrI4 in liquid AlI3 at a temperature of 280–300 °C with metallic zirconium or aluminium.[3][4]

Structure and bonding

Zirconium(III) iodide has a lower magnetic moment than is expected for the d1 metal ion Zr3+, indicating non-negligible Zr–Zr bonding.[2]

The crystal structure of zirconium(III) iodide is based on hexagonal close packing of iodide ions with one third of the octahedral interstices occupied by Zr3+ ions.[2] The structure consists of parallel chains of face-sharing {ZrI6} octahedra[5] with unequally spaced metal atoms. The Zr–Zr separation alternates between 3.17 Å and 3.51 Å.[6]

ZrCl3, ZrBr3 and ZrI3 adopt structures very similar to the β-TiCl3 structure.[2] In all three ZrX3 there is some elongation of the octahedra along the metal-metal axis, partly due to metal-metal repulsion,[4] but the elongation is most pronounced in the chloride, moderate in the bromide and negligible in the iodide.[4]

References

  1. ^ William M. Haynes, ed. (2013). CRC Handbook of Chemistry and Physics (94th ed.). CRC Press. p. 4-101. ISBN 978-1466571143.
  2. ^ a b c d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.
  3. ^ Larsen, E. M.; Moyer, James W.; Gil-Arnao, Francisco; Camp, Michael J. (1974). "Synthesis of crystalline zirconium trihalides by reduction of tetrahalides in molten aluminum halides. Nonreduction of hafnium". Inorg. Chem. 13 (3): 574–581. doi:10.1021/ic50133a015.
  4. ^ a b c Larsen, Edwin M.; Wrazel, Julie S.; Hoard, Laurence G. (1982). "Single-crystal structures of ZrX3 (X = Cl−, Br−, I−) and ZrI3.40 synthesized in low-temperature aluminum halide melts". Inorg. Chem. 21 (7): 2619–2624. doi:10.1021/ic00137a018.
  5. ^ Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford University Press. pp. 418–419. ISBN 978-0-19-965763-6.
  6. ^ Lachgar, Abdessadek; Dudis, Douglas S.; Corbett, John D. (1990). "Revision of the structure of zirconium triiodide. The presence of metal dimers". Inorg. Chem. 29 (12): 2242–2246. doi:10.1021/ic00337a013.
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