Trirhenium nonachloride

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Trirhenium nonachloride
Re3Cl12 cluster subunit in ReCl3
IUPAC name
Rhenium(III) chloride
Other names
Rhenium trichloride
3D model (Jmol)
ECHA InfoCard 100.033.610
EC Number 236-987-1
Molar mass 292.57 g/mol
Appearance red, crystalline, nonvolatile solid
Density 4800 kg/m3
Melting point N/A
Boiling point 500 °C (932 °F; 773 K) (decomposes)
hydrolyzes to form Re2O3.xH2O.
Rhombohedral, hR72
R-3m, No. 166
(trimeric solid and in solution)
(dimeric in acetic acid)
Main hazards Corrosive (C)
Safety data sheet External MSDS
Related compounds
Other anions
Rhenium tribromide
Rhenium triiodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Trirhenium nonachloride is a compound with the formula ReCl3, sometimes also written Re3Cl9. It is a dark red hygroscopic solid that is insoluble in ordinary solvents. The compound is important in the history of inorganic chemistry as an early example of a cluster compound with metal-metal bonds.[1] It is used as a starting material for synthesis of other rhenium complexes.

Structure and physical properties[edit]

As shown by X-ray crystallography trirhenium nonachloride consists of Re3Cl12 subunits that share three chloride bridges with adjacent clusters. The interconnected network of clusters forms sheets. Around each Re center are seven ligands, four bridging chlorides, one terminal chloride, and two Re-Re bonds.[2]

Re3Cl12 cluster within ReCl3, shown with full coordination sphere around each chloride.

The heat of oxidation is evaluated according to the equation:

1/3 Re3Cl9 + 4 OH + 2 OCl → ReO4 + 2 H2O + 5Cl

The enthalpy for this process is 190.7 ± 0.2 kcal/mol.[2]


The compound was discovered in 1932, although these workers did not determine the remarkable structure of this compound.[3] Trirhenium nonachloride is efficiently prepared by thermal decomposition of rhenium pentachloride or hexachlororhenic(IV) acid:[4]

3 ReCl5 → Re3Cl9 + 3 Cl2

If the sample is vacuum sublimed at 500 °C, the resulting material is comparatively unreactive, but the partially hydrated material can be more useful synthetically. Other synthetic methods include treating rhenium with sulfuryl chloride. This process is sometimes conducted with the addition of aluminium chloride.[2] It is also obtained by heating Re2(O2CCH3)4Cl2 under HCl:

3/2 Re2(O2CCH3)4Cl2 + 6 HCl → Re3Cl9 + 6 HO2CCH3


  1. ^ Cotton, F. A.; Walton, R. A. “Multiple Bonds Between Metal Atoms” Oxford (Oxford): 1993. ISBN 0-19-855649-7.
  2. ^ a b c Colton, R. Chemistry of rhenium and technetium. 965.
  3. ^ Geilnann, W.; Wriuce, F. W.; Biltz. W.: Nachr. Ges. Wiss. Gottingen 1932, 579.
  4. ^ Lincoln R.; Wilkinson, G. (1980). "Trirhenium Nonachloride". Inorg. Synth. Inorganic Syntheses. 20: 44. doi:10.1002/9780470132517.ch12. ISBN 978-0-470-13251-7.