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On the Dewar-Chatt-Duncanson model for catalytic gold(I) complexes
Nicola Salvi1, Leonardo Belpassi, Francesco Tarantelli
1Dipartimento di Chimica, Università di Perugia and I.S.T.M.-C.N.R. 06123 Perugia, Italy.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|May 15, 2010
Summary
This study reveals that gold-substrate bonds in catalytic intermediates feature significant pi back-donation, challenging previous assumptions. This back-donation is tunable by ligand choice and structural factors.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Computational Chemistry
Background:
- The Dewar-Chatt-Duncanson model describes bonding in metal-ligand interactions.
- Understanding donation and back-donation is crucial for catalytic mechanisms.
- Gold(I) complexes with N-heterocyclic carbenes or chloride ligands are relevant in catalysis.
Purpose of the Study:
- To provide a model-free definition and theoretical analysis of electron-charge displacements in L-Au(I)-S catalytic intermediates.
- To investigate the donation and back-donation components of the gold-substrate bond.
- To challenge the prevailing view on the relative contributions of sigma donation and pi back-donation.
Main Methods:
- Rigorous model-free theoretical analysis.
- Detailed examination of electron-charge displacements.
- Analysis of realistic catalytic intermediates (L-Au(I)-S).
Main Results:
- The gold-substrate bond is characterized by substantial pi back-donation, often comparable to sigma donation.
- Pi back-donation is a highly tunable component of the gold-substrate bond.
- Back-donation is influenced by the auxiliary ligand (L) and structural factors like bond lengths and carbon pyramidalization.
Conclusions:
- The significant role of pi back-donation in gold-substrate bonding is confirmed.
- The tunability of back-donation offers opportunities for catalyst design.
- This work refines the understanding of bonding in gold-catalyzed reactions.
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