Trirhenium nonachloride is a

compound Compound may refer to: Architecture and built environments * Compound (enclosure), a cluster of buildings having a shared purpose, usually inside a fence or wall ** Compound (fortification), a version of the above fortified with defensive struc ...

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 Inorganic chemistry deals with chemical synthesis, synthesis and behavior of inorganic compound, inorganic and organometallic chemistry, organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subj ...

as an early example of a cluster compound with metal-metal bonds. It is used as a starting material for synthesis of other rhenium complexes.

Structure and physical properties

As shown by

X-ray crystallography X-ray crystallography is the experimental science of determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to Diffraction, diffract in specific directions. By measuring th ...

trirhenium nonachloride consists of Re₃Cl₁₂ subunits that share three chloride

bridges A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somet ...

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.Colton, R. Chemistry of rhenium and technetium. 965. The

hydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

is molecular with the formula Re₃Cl₉(H₂O)₃. 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.

Preparation and reactions

The compound was discovered in 1932. Trirhenium nonachloride is efficiently prepared by thermal decomposition of rhenium pentachloride or hexachlororhenic(IV) acid: :3 ReCl₅ → Re₃Cl₉ + 3 Cl₂ If the sample is vacuum sublimed at 500 °C, the resulting material is comparatively unreactive. The partially hydrated material such as can be more useful synthetically. Other synthetic methods include treating

rhenium Rhenium is a chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...

with

sulfuryl chloride Sulfuryl chloride is an inorganic compound with the formula SO2Cl2. At room temperature, it is a colorless liquid with a pungent odor. Sulfuryl chloride is not found in nature. Sulfuryl chloride is commonly confused with thionyl chloride, SOC ...

. This process is sometimes conducted with the addition of

aluminium chloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms a hexahydrate with the formula , containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are col ...

. It is also obtained by heating Re₂(O₂CCH₃)₄Cl₂ under HCl: :3/2 Re₂(O₂CCH₃)₄Cl₂ + 6 HCl → Re₃Cl₉ + 6 HO₂CCH₃ Reaction of the tri- and pentachlorides gives rhenium tetrachloride: :3 ReCl₅ + Re₃Cl₉ → 6 ReCl₄

References

{{Chlorides Rhenium Trichloride Chlorides Metal halides Substances discovered in the 1930s