Selective B(3)-H Activation Affording Multinuclear Ir(III) Complexes with (o-Carboranyl)dithioester Ligands

Area of Science:

• Organometallic Chemistry
• Boron Chemistry
• Coordination Chemistry

Background:

• Carboranes are versatile boron-containing clusters with unique electronic properties.
• Developing efficient methods for functionalizing carboranes and incorporating them into metal complexes is crucial.
• Direct C-H or B-H activation offers atom-economical routes to complex organometallic structures.

Purpose of the Study:

• To synthesize novel carboranyl dithioester bridging ligands.
• To achieve direct B-H activation of these ligands using an iridium(III) precursor.
• To characterize the resulting bimetallic or trimetallic complexes and confirm selective activation.

Main Methods:

• Synthesis of carboranyl dithioester ligands via in situ substitution reactions.
• Direct B-H activation using a half-sandwich iridium(III) complex ([Cp*IrCl2]2).
• Characterization of products using single crystal X-ray diffraction and other spectroscopic techniques.

Main Results:

• A series of carboranyl dithioester ligands linking two or three o-carborane units were successfully synthesized.
• Direct B-H activation of these ligands by [Cp*IrCl2]2 was achieved without the need for silver(I) or alkali metals.
• The formation of bimetallic and trimetallic iridium(III) complexes was confirmed, with selective B(3)-H activation.
• SnCl2-inserted derivatives further supported the selective B(3)-H activation.

Conclusions:

• Novel carboranyl dithioester ligands enable efficient direct B-H activation pathways.
• This methodology provides a facile route to diverse bimetallic and trimetallic carborane-iridium complexes.
• The selective activation at the B(3) position highlights the controlled reactivity of these carborane systems.