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Olefin metathesis (Chauvin mechanism) template

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Chauvin cycle of a Grubbs-catalysed cross metathesis of two terminal alkenes: [2+2] cycloaddition of the Ru methylidene to R¹CH=CH₂, retro-[2+2] releasing ethene, then the same with CH₂=CHR² releasing R¹CH=CHR²; key step: [2+2] cycloaddition with curly arrows.

What the template shows

A metal carbene and an alkene trade partners through a metallacyclobutane
Overall: R¹CH=CH₂ + CH₂=CHR² ⇌ R¹CH=CHR² + CH₂=CH₂↑ (cat. Grubbs Ru carbene)
[Ru] = RuCl₂(NHC)
Grubbs II, after loss of PCy₃
Chauvin (1971) proposed the metal-carbene / metallacyclobutane mechanism (Nobel Prize 2005 with Grubbs and Schrock).
Every step is reversible; loss of gaseous ethene drives cross metathesis and ring-closing metathesis (RCM).
Grubbs II (RuCl₂(PCy₃)(H₂IMes)=CHPh) enters the cycle after losing PCy₃ to give the 14-electron species.
Schrock Mo and W alkylidenes run the same cycle and are more reactive but air-sensitive.
Key step: [2+2] cycloaddition
The Ru=C and C=C π bonds combine into two new σ bonds (C–C and Ru–C), giving the four-membered metallacycle; cleaving it the other way round makes the new carbene and the new alkene.
[Ru] = RuCl₂(H₂IMes); the ligands are named in the centre, not drawn · every part of this figure is editable

Drawn with 28 atoms, 7 arrows, 67 shapes – every one editable in MolDraw.

Sources

Hérisson & Chauvin, Makromol. Chem. 1971, 141, 161 Original paper
Grubbs, Angew. Chem. Int. Ed. 2006, 45, 3760 Review
Crabtree, The Organometallic Chemistry of the Transition Metals, 6th ed., Wiley 2014 Textbook

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Frequently asked questions

Is the Olefin metathesis (Chauvin mechanism) template free?

Yes. The Olefin metathesis (Chauvin mechanism) template is one of the free MolDraw templates: open it in the editor or download it from this page as SVG or PNG and use it in your slides, worksheets and notes.

Can I edit the Olefin metathesis (Chauvin mechanism) template?

Yes. It opens as an ordinary MolDraw drawing, so every structure, arrow, label and colour can be changed, and you can add your own content around it.

Is the chemistry checked?

Every structure is checked with RDKit and every curly arrow passes MolDraw’s electron-flow audit. The sources used are listed on this page.

What does a catalytic cycle template show?

The active catalyst, each intermediate around the cycle, the substrates that enter and the products that leave, with each elementary step named on its arrow.