Anionic N-heterocyclic carbenes featuring weakly coordinating perfluoroalkylphosphorane moieties

Area of Science:

• Organometallic Chemistry
• Ligand Design
• Supramolecular Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Developing NHCs with tailored electronic and steric properties is crucial for advancing catalysis.
• Weakly coordinating anions (WCAs) are essential for stabilizing reactive intermediates and enhancing catalytic activity.

Purpose of the Study:

• To synthesize and characterize a novel class of NHCs bearing weakly coordinating anions (WCA-NHCs).
• To explore the coordination chemistry of these new WCA-NHCs with selenium and gold complexes.
• To investigate the electronic and steric properties of WCA-NHCs and their metal complexes.

Main Methods:

• Deprotonation of functionalized methylimidazole and imidazolate precursors.
• Synthesis of anionic selenium adducts and WCA-NHC gold complexes.
• Structural and spectroscopic characterization (NMR, X-ray crystallography).
• Quantum chemical calculations to elucidate electronic and steric properties.

Main Results:

• High-yield synthesis of anionic WCA-NHCs 3 and 4.
• Formation of an anionic selenium adduct (5) and WCA-NHC gold complexes (6 and 7).
• Detailed structural and spectroscopic data revealing unique properties of WCA-NHCs.
• Computational analysis confirming strong σ-donor and π-acceptor abilities.

Conclusions:

• The synthesized WCA-NHCs represent a new class of ligands with unique characteristics.
• These ligands exhibit a combination of weakly coordinating periphery, negative charge, and tunable electronic properties.
• WCA-NHCs show significant potential as versatile ligands in coordination chemistry and catalysis due to their distinct steric and electronic profiles.