Anionic and zwitterionic carboranyl N-heterocyclic carbene Au(i) complexes

Area of Science:

• Organometallic Chemistry
• Coordination Chemistry
• Materials Science

Background:

• N-heterocyclic carbenes (NHCs) are versatile ligands in organometallic chemistry.
• Carboranes are unique boron-rich clusters with diverse applications.
• The development of novel NHC ligands is crucial for advancing catalysis and materials science.

Purpose of the Study:

• To report the synthesis of the first carboranyl N-heterocyclic carbene (NHC) complexes.
• To investigate the reactivity of these novel NHCs with gold precursors.
• To characterize the resulting gold-NHC adducts and evaluate their structural properties.

Main Methods:

• Synthesis of unsymmetrical mono-anionic and symmetrical dianionic carboranyl NHCs.
• Reaction of NHCs with chloro(dimethyl sulfide)gold(I) (ClAuSMe2).
• Characterization using NMR spectroscopy, mass spectrometry, and single crystal X-ray diffraction.
• Calculation of percent buried volume (%Vbur) to assess steric properties.

Main Results:

• Successful synthesis of novel carboranyl NHC ligands.
• Formation of unusual zwitterionic and anionic gold(I) dimethyl sulfide adducts.
• X-ray diffraction confirmed the structures of the synthesized compounds.
• Replacement of adamantyl groups with carborane moieties increased steric bulk by 3.7% (%Vbur).

Conclusions:

• The first carboranyl NHC-metal complexes have been successfully synthesized.
• These novel NHCs form unique gold(I) adducts with significant steric profiles.
• The increased %Vbur suggests potential for enhanced stability or altered reactivity in catalytic applications.