chemistry

IMes

IMes 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 IMes rather than just read about it. In short: IMes is an abbreviation for an organic compound that is a common ligand in organometallic chemistry. It is an N-heterocyclic carbene (NHC).

Key takeaways

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

Reference excerpt

IMes is an abbreviation for an organic compound that is a common ligand in organometallic chemistry. It is an N-heterocyclic carbene (NHC). The compound, a white solid, is often not isolated but instead is generated upon attachment to the metal centre. First prepared by Anthony J. Arduengo, the heterocycle is synthesized by condensation of 2,4,6-trimethylaniline and glyoxal to give the diimine. In the presence of acid, the resulting glyoxal-bis(mesitylimine) condenses with formaldehyde to give the dimesitylimidazolium cation. This cation is the conjugate acid of the NHC.

Related compounds Bulkier than IMes is the NHC ligand IPr (CAS 244187-81-3). IPr features diisopropylphenyl in place of the mesityl substituents. Some variants of IMes and IPr have saturated backbones, two such ligands are SIMes and SIPr. They are prepared by alkylation of substituted anilines with dibromoethane followed by ring closure and dehydrohalogenation of the dihydroimidazolium salt.

References

Further reading Bantreil, Xavier; Nolan, Steven P. (2011). "Synthesis of N-heterocyclic carbene ligands and derived ruthenium olefin metathesis catalysts". Nature Protocols. 6 (1): 69–77. doi:10.1038/nprot.2010.177. PMID 21212784. S2CID 30604456.

Illustrations

Worked examples

Example 1 — a first encounter with IMes

Start with the simplest possible case. Write down what IMes 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 IMes 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 IMes 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 IMes

In research: IMes 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 IMes 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: IMes is common in secondary-school and first-year university syllabi. It links to neighbouring topics Carbenes, Ligands, Organometallic chemistry, so understanding it makes those chapters shorter.
In everyday life: Look for IMes 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.

Affiliate

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

How to study IMes in 20 minutes

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

Frequently asked questions

What is IMes in simple terms?

IMes is an abbreviation for an organic compound that is a common ligand in organometallic chemistry. It is an N-heterocyclic carbene (NHC).

Why does IMes 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 IMes?

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 IMes.