This document discusses metal cyclopentadiene complexes, including their preparation, properties, and bonding. It introduces cyclopentadiene, noting that it dimerizes at room temperature and is used as a precursor for metallocenes. Metal cyclopentadiene complexes can be prepared by reacting sodium cyclopentadienide with metal halides like nickel chloride. Cyclopentadiene is used as a precursor for catalysis and copolymers, and can be semi-hydrogenated to form cyclopentene. It is also a precursor in the synthesis of compounds like dodecahedrane.

1. Dr. Geeta Tewari
Department of Chemistry
D. S. B. Campus
Kumaun University, Nainital
Email: geeta_k@rediffmail.com
Metal Cyclopentadiene Complexes
Preparation, Properties, Bonding
CC BY-SA

2. Cyclopentadiene complexes- Introduction
Diene
• Covalent compound containing two double bonds, usually
between carbon atoms
• Diene is a spectator ligand and used as chelating ligand.
Cumulated dienes: Double bond sharing between common carbon
atoms (allene)
Conjugated dienes: Alternative single and double bond
Unconjugated dienes: Double bonds are separated by two or more
carbon-carbon single bond.

3. Cyclopentadiene complexes- Introduction
C5H6 (CpH)
It dimerizes at room temperature via Diels-Alder
reaction to form dicyclopentadiene.
Precursor of Cp
-
Used for the preparation of metallocene.
2NaC5H5 + NiCl2 → Ni(C5H5)2 + NaCl

4. Organometallic with both CpH and Cp
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Cyclopentadiene complexes- Preparation

5. Organometallic with both CpH and Cp
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Cyclopentadiene complexes- Preparation

6. Organometallic with both CpH and Cp
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Cyclopentadiene complexes- Preparation

7. Cyclopentadiene- Uses
 Precursor of cyclopentadienyl-based catalysis
 Precursor of comonomers (polymerization precursor of a
copolymer)

8. Cyclopentadiene- Uses
• Semi-hydrogenation gives cyclopentene.

9. https://en.wikipedia.org/wiki/File:DodecahedranePrecursorSynthesis.png
Cyclopentadiene- Preparation of dodecahedrane

10. Cyclopentadiene- Formation of derivatives

11. Synthesis of cyclopentadienyl complexes

12. Synthesis of cyclopentadienyl complexes

13. Thank You