chemistry

Potassium octachlorodirhenate

Potassium octachlorodirhenate is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Potassium octachlorodirhenate rather than just read about it. In short: Potassium octachlorodirhenate(III) is an inorganic compound with the formula K2Re2Cl8. This dark blue salt is well known as an early example of a compound featuring quadruple bond between its metal centers.

Key takeaways

Potassium octachlorodirhenate belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Potassium octachlorodirhenate to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Potassium octachlorodirhenate from memory before moving on to harder problems.

Reference excerpt

Potassium octachlorodirhenate(III) is an inorganic compound with the formula K2Re2Cl8. This dark blue salt is well known as an early example of a compound featuring quadruple bond between its metal centers. Although the compound has no practical value, its characterization was significant in opening a new field of research into complexes with quadruple bonds.

Synthesis and reactions Soviet chemists first reported K2[Re2Cl8] in 1954, but it was not until 1964 that Cotton and Harris characterized the compound as featuring a short Re–Re bond, the first of its kind discovered. The results of this classic study subsequently led to new work into other metals capable of forming metal–metal bonds, such as chromium, molybdenum, tungsten, and technetium. A high-yield synthesis of the tetrabutylammonium salt involves treating the perrhenate salt with benzoyl chloride followed by HCl:

2 [(n-C4H9)4N]ReO4 + 8 C6H5COCl → [(n-C4H9)4N]2[Re2Cl8] + organic products

Octachlorodirhenate(III) is a precursor to other complexes with multiply-bonded rhenium centers as the quadruple bond is quite stable and is often maintained in ligand substitution reactions. For example, upon treatment with concentrated HBr, the complex forms the analogous anion [Re2Br8]2−, which can easily be converted into other dirhenium species.

Structure and bonding

In the [Re2Cl8]2−, the Re–Re bond distance is 2.24 Å, the Re–Re–Cl bond angles are 104°, and the Cl–Re–Cl angles are 87°. The chloride ligands are fully eclipsed. Although this geometry results in repulsive interactions between the chloride ions, this conformation allows for maximum δ–δ overlap between the Re(III) centers, a factor which overrides the unfavorable chloride repulsions. The [Re2Cl8]2− anion has a weak electrophilic character. With the configuration, Re(III) is well suited to engage in quadruple bonding. Electrons are allocated to give the configuration σ2π4δ2, resulting in a bond order of 4 between the rhenium centers. The brilliant color of the [Re2Cl8]2− arises from the δ→δ* electronic transition.

References

Illustrations

Worked examples

Example 1 — a first encounter with Potassium octachlorodirhenate

Start with the simplest possible case. Write down what Potassium octachlorodirhenate claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Potassium octachlorodirhenate before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Potassium octachlorodirhenate ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Potassium octachlorodirhenate

In research: Potassium octachlorodirhenate appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Potassium octachlorodirhenate in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Potassium octachlorodirhenate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chemical compounds containing metal–metal bonds, Chloro complexes, Potassium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Potassium octachlorodirhenate outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Potassium octachlorodirhenate” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Potassium octachlorodirhenate in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Potassium octachlorodirhenate means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Potassium octachlorodirhenate out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Potassium octachlorodirhenate in simple terms?

Why does Potassium octachlorodirhenate matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Potassium octachlorodirhenate?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Potassium octachlorodirhenate.