Complexes Bearing Protic N-Heterocyclic Carbene Ligands
Shigeki Kuwata1, F Ekkehardt Hahn2
1School of Materials and Chemical Technology , Tokyo Institute of Technology , 2-12-1 O-okayama , Meguro-ku, Tokyo 152-8552 , Japan.
Chemical Reviews
|June 26, 2018
Summary
Protic N-heterocyclic carbenes (pNHCs) offer unique reactivity due to their NH group. This review covers their synthesis, properties, and catalytic applications, highlighting their potential in coordination chemistry.
Area of Science:
- Organometallic Chemistry
- Coordination Chemistry
- Catalysis
Background:
- Protic N-heterocyclic carbenes (pNHCs) are less studied than conventional NHCs.
- Their NH group imparts distinct properties and reactivity.
- Free pNHCs are unstable, isomerizing to azoles, but their metal complexes are accessible.
Purpose of the Study:
- To review the coordination chemistry of pNHCs.
- To explore synthetic strategies for pNHC-metal complexes.
- To discuss the properties, reactivity, and catalytic roles of pNHC complexes.
Main Methods:
- Literature review of synthetic methods for pNHC complexes.
- Analysis of coordination chemistry and reactivity data.
- Examination of pNHC involvement in catalytic cycles.
Main Results:
- Various synthetic routes to pNHC transition-metal complexes have been established.
- The Brønsted-acidic NH group is a key feature influencing reactivity.
- pNHC ligands participate in catalytically active species and cooperative catalysis.
Conclusions:
- pNHC complexes represent a developing area in organometallic chemistry.
- Their unique electronic and steric properties enable novel catalytic transformations.
- Further research into pNHC coordination chemistry promises advancements in catalysis.
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