Rhodapentalenes: Pincer Complexes with Internal Aromaticity

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Aromaticity Studies

Background:

• Pincer complexes are known for stability and tunability, typically with non-aromatic metallacyclic cores.
• Aromaticity in peripheral organic rings is crucial for the properties of classical pincer complexes.

Purpose of the Study:

• To report the synthesis and characterization of rhodapentalenes, a novel class of pincer complexes.
• To investigate the aromatic character of their metallacyclic cores and explore their unique chemical behavior.

Main Methods:

• Experimental studies including synthesis and characterization.
• Computational studies to analyze electronic structure and bonding.
• Investigation of reaction mechanisms, including dearomatization-aromatization processes.

Main Results:

• Rhodapentalenes exhibit significant aromatic character within their metallacyclic cores.
• These complexes display good thermal stability despite fragile rhodium-carbon bonds.
• Observed dearomatization-aromatization reactions indicative of metal-ligand cooperation.

Conclusions:

• The stabilization of rigid CCC pincer architectures and intrinsic metallacyclic aromaticity are key to these rhodium species.
• Introduces a new concept of internal aromaticity involving metal d-orbitals in pincer chemistry.
• Findings pave the way for novel construction motifs and applications in organometallic chemistry.