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Industrial Catalysis
Lecture for Makrokierunek
Lecture 2
Homogeneous Catalysis by Transition Metals
-Introduction
Nikodem Kuźnik
Silesian University of
Technology
Gliwice, Poland
Lecture 2
Scope of the lecture
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Definition of coordination compound, organometallics
Structure of complexes
Types of ligands
Parameters of complexes (CN, OS, EN)
Key reactions
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De/coordination of neutral ligand
Ligand exchange
Oxidative addition / reductive elimination
De/insertion (β-elimination)
Definition of complexes
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Coordination (complex) compound
Valency (Coordination Number CN) ≠ Oxidation State (OS)
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Organometallics
Bond: C – A A = any less electronegative element
Complex Structure
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Metal center(s)
Ligand(s)
Inter/outer coordination sphere
Ligand classification
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Neutral ligands
H2O, NH3, H2, CO, PR3, alkenes, …
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Ionic ligands
H, F, Cl, Br, I, OH, alkyl, OR, …
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Chelation
phosphines, polyalkenes, polyamines, …
„18 Electron rule”
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d-block elements tend to achieve 18 e
Intert electron pair effect (Pd, Pt, …)
f-block elements 32 e
How to count electron number (EN)?
Ionic ligans: 1 e
Neutral ligands: 2 e
Element’s electrons: valence electrons
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Consequences
Key reactions
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De/coordination of neutral ligand
Ligand exchange
Oxidative addition / reductive elimination
De/insertion (β-elimination)
Transmetallation
Others
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Lewis acid de/coordination
σ-bond metathesis
H abstraction
ortho-metallation
De/coordination of neutral ligand
Intermolecular process!
[RhH(CO)(PPh3)3] → [RhH(CO)(PPh3)2] + PPh3
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ΔEN = -2, ΔCN = -1, ΔOS = 0
[Fe(CO)5] → [Fe(CO)4] + CO
ΔEN = -2, ΔCN = -1, ΔOS = 0
[RhH(CO)(PPh3)2] + ethene → [RhH(CO)(ethene)(PPh3)2]
ΔEN = +2, ΔCN = +1, ΔOS = 0
Ligand exchange
[Co(NH3)6]3+ + 6H2O → [Co(H2O)6]3+ +6NH3
ΔEN = 0, ΔCN = 0, ΔOS = 0
[Co(NH3)6]3+ + 3 en → [Co(en)3]3+ +6NH3
[RuCl2(PPh3)3]+ethene→ [RhCl2(ethene) (PPh3)2] +PPh3
ΔG=-67 kJ/mol
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Chelation effect
Possible mechanism: dissociative,
associative, intermediates
Oxidative addition–reductive elimination
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[IrCl(H)2(CO)(PPh3)2]→[IrCl(CO)(PPh3)2]+H2
ΔEN = -2, ΔCN = -2, ΔOS = -2
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Mg + CH3CH2Br → Mg(Br)CH2CH3
ΔEN = +2, ΔCN = +2, ΔOS = +2
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syn orientation!
Br
+
Pd
PPh3
PPh3
Br
Pd
PPh3
PPh3
ΔEN = +2, ΔCN = +2, ΔOS = +2
De/insertion
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Intramolecular process
syn orientation!
CH3
H H
H
Rh
Cl
PPh3
H
H
PPh3
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Rh
Cl
H
H
H
CH3
H
PPh3
PPh3
ΔEN = -2, ΔCN = -1, ΔOS = -0
CO
C
Me
Mn
OC
Mn
CO
CO
Me
O
OC
CO
CO