chemistry

Molybdenum(V) chloride

Molybdenum(V) chloride 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 Molybdenum(V) chloride rather than just read about it. In short: Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds.

Key takeaways

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

Reference excerpt

Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents.

Structure

Usually called molybdenum pentachloride, it is in fact partly a dimer with the molecular formula Mo2Cl10. In the dimer, each molybdenum has local octahedral symmetry and two chlorides bridge between the molybdenum centers. A similar structure is also found for the pentachlorides of W, Nb and Ta. In the gas phase and partly in solution, the dimers partially dissociate to give a monomeric MoCl5. The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center.

Preparation and properties MoCl5 is prepared by chlorination of Mo metal but also chlorination of MoO3. The unstable hexachloride MoCl6 is not produced in this way. MoCl5 is reduced by acetonitrile:

2 MoCl5 + 5 CH3CN → 2 MoCl4(CH3CN)2 + HCl + ClCH2CN Molybdenum(IV) bromide is prepared by treatment of MoCl5 with hydrogen bromide:

2 MoCl5 + 10 HBr → 2 MoBr4 + 10 HCl + Br2 The reaction proceeds via the unstable molybdenum(V) bromide, which releases bromine at room temperature. MoCl5 is a good Lewis acid toward non-oxidizable ligands. It forms an adduct with chloride to form [MoCl6]−. In organic synthesis, the compound finds occasional use in chlorinations, deoxygenation, and oxidative coupling reactions. Although it polymerizes tetrahydrofuran, MoCl5 is stable in diethyl ether. Reduction of such solutions with tin gives MoCl4((CH3CH2)2O)2 and MoCl3((CH3CH2)2O)3, depending on conditions.

Safety considerations MoCl5 is an aggressive oxidant and readily hydrolyzes to release HCl.

See also Molybdenum(IV) chloride Molybdenum(VI) chloride Molybdenum(V) fluoride Tungsten(V) chloride

References

Illustrations

Worked examples

Example 1 — a first encounter with Molybdenum(V) chloride

Start with the simplest possible case. Write down what Molybdenum(V) chloride 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 Molybdenum(V) chloride 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 Molybdenum(V) chloride 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 Molybdenum(V) chloride

In research: Molybdenum(V) chloride 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 Molybdenum(V) chloride 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: Molybdenum(V) chloride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chlorides, Inorganic compounds, Molybdenum(V) compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Molybdenum(V) chloride 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.

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How to study Molybdenum(V) chloride in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Molybdenum(V) chloride 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 Molybdenum(V) chloride out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Molybdenum(V) chloride in simple terms?

Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds.

Why does Molybdenum(V) chloride 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 Molybdenum(V) chloride?

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 Molybdenum(V) chloride.