Tungsten(VI) N-Heterocyclic Carbene Complexes: Synthetic, Structural, and Computational Study

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Computational Chemistry

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Tungsten oxyhalides are reactive precursors for various tungsten complexes.

Purpose of the Study:

• To synthesize and characterize a new tungsten oxychloride adduct with an NHC ligand.
• To investigate the hydrolysis behavior of the synthesized adduct.
• To explore the electronic structure and bonding of the tungsten-carbene interaction using DFT.

Main Methods:

• Synthesis of [WOCl4(Idipp)] adduct.
• Spectroscopic characterization (NMR, IR).
• X-ray crystallography of [WO2Cl2(Idipp)].
• Density Functional Theory (DFT) calculations.

Main Results:

• Formation of a 1:1 adduct, [WOCl4(Idipp)], confirmed by spectroscopy and DFT.
• Rapid hydrolysis to imidazolium salts upon air exposure.
• Slow hydrolysis to form [WO2Cl2(Idipp)], characterized crystallographically.
• DFT analysis reveals a primary sigma-donor carbene-metal interaction.
• Computational studies propose a low-energy hydrolysis mechanism.

Conclusions:

• The reaction of WOCl4 with Idipp yields a stable adduct with significant sigma-donor carbene-metal bonding.
• The adduct is susceptible to hydrolysis, forming various tungsten species and imidazolium salts.
• DFT calculations provide valuable insights into the structure, bonding, and reaction pathways.