Bulky cyclopentadienyl ligands

Structure of tBu3C5H3, a prototypical bulky cyclopentadiene.

In the area of organometallic chemistry, a bulky cyclopentadienyl ligand is jargon for a ligand of the type C5H5−nR−n where R is a branched alkyl and n = 3 or 4. Representative examples are the tetraisopropyl derivative C5HiPr−4 and the tris(tert-butyl) derivative 1,2,4-C5H2tBu−3. These ligands are so large that their complexes behave differently from the analogues derived from pentamethylcyclopentadienyl, itself a bulky ligand.

## Contents

* 1 General properties of complexes
* 2 Synthesis and reactions
* 3 Related bulky ligands
* 4 References

## General properties of complexes

Because they cannot closely approach the metal, these bulky ligands can stabilize high spin complexes, such as (C5H2tBu3)2Fe2I2. These large ligands stabilize highly unsaturated derivatives such as (C5H2tBu3)2Fe2N2.

## Synthesis and reactions

Structure of (tBu3C5H2)2Fe2N2.

The (tert-butyl)cyclopentadiene is prepared by alkylation of cyclopentadiene with tert-butyl bromide in the presence of sodium hydride and dibenzo-18-crown-6.[1] The intermediate in this synthesis is di-tert-butylcyclopentadiene. This compound is conveniently prepared by alkylation of cyclobutadiene with tert-butyl bromide under phase-transfer conditions.[2][1]

Illustrative of the unusual complexes made possible with these bulky ligands is molecular iron nitrido complex (tBu3C5H2)2Fe2N2.[3] In contrast to (C5Me5)2Ir2Cl4, (tBu3C5H2)IrCl2 is monomeric.[4]

## Related bulky ligands

Less bulky ligand are of the type C

3R−
2 where R is a branched alkyl. Examples include the di-tert-butyl and related trimethylsilyl derivatives. One such complex is U(C

3(SiMe

3.[5]

## References

1. ↑ 1.0 1.1 Reiners, Matthias; Ehrlich, Nico; Walter, Marc D. (2018). "Synthesis of Selected Transition Metal and Main Group Compounds with Synthetic Applications". Inorganic Syntheses. 37. p. 199. doi:10.1002/9781119477822.ch8. ISBN 978-1-119-47782-2.
2. ↑ Hyster, Todd K. (2015). "1,3-Di-tert-butylcyclopentadiene". Encyclopedia of Reagents for Organic Synthesis. pp. 1–2. doi:10.1002/047084289X.rn01866. ISBN 9780470842898.
3. ↑ Reiners, Matthias; Maekawa, Miyuki; Daniliuc, Constantin G.; Freytag, Matthias; Jones, Peter G.; White, Peter S.; Hohenberger, Johannes; Sutter, Jörg et al. (2017). "Reactivity studies on [Cp′Fe(μ-I)]2: Nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation". Chemical Science 8 (5): 4108–4122. doi:10.1039/C7SC00570A. PMID 30155215.
4. ↑ Shimogawa, Ryuichi; Takao, Toshiro; Suzuki, Hiroharu (2017). "Half-sandwich Cyclopentadienyl Iridium Dichloride Monomer Cp‡IrCl2 (Cp‡ = 1,2,4-tri-tert-butylcyclopentadienyl)". Chemistry Letters 46 (2): 197–199. doi:10.1246/cl.160937.
5. ↑ Eralie, Dylan M. T.; Ducilon, John; Gorden, Anne E. V. (2025). "Uranium Chemistry: Identifying the Next Frontiers". Inorganic Chemistry 64 (2): 767–784. doi:10.1021/acs.inorgchem.4c02173. PMID 39190695.

* v
* t
* e

Organometallic chemistry

Principles|

* crystal field theory
* ligand field theory
* 18-electron rule
* polyhedral skeletal electron pair theory
* isolobal principle
* π backbonding
* hapticity
* d electron count
* spin states

Reactions|

* oxidative addition / reductive elimination
* migratory insertion
* β-hydride elimination
* transmetalation
* carbometalation

Types of compounds|

* Gilman reagents
* Grignard reagents
* cyclopentadienyl complexes
* metallocenes
* sandwich compounds
* half sandwich compounds
* transition metal carbene complexes
* transition metal carbyne complexes

Applications|

* Monsanto process
* Ziegler–Natta process
* Shell higher olefin process
* olefin metathesis

Related branches of chemistry|

* organic chemistry
* inorganic chemistry
* bioinorganic chemistry

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Bulky cyclopentadienyl ligands. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Chemistry:Bulky_cyclopentadienyl_ligands&oldid=4308784"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template