C_sp-H/F bond activation and borylation with iron

Area of Science:

• Organometallic Chemistry
• Catalysis
• Synthetic Chemistry

Background:

• Iron complexes are increasingly explored as alternatives to precious metals in catalysis.
• Nitrogen fixation and C-H activation are fundamental transformations in chemistry.

Purpose of the Study:

• To develop a synthetic cycle for heterolytic benzene C-H activation and subsequent borylation.
• To investigate the reactivity of a specific potassium-iron-dinitrogen complex.

Main Methods:

• Reduction of a potassium-iron-dinitrogen complex with KC8 and 18-C-6 crown ether.
• Reaction of the resulting complex with benzene and fluorobenzene to achieve C-H and C-F bond cleavage.
• Borylation of the activated intermediates using diboron reagents and chloroboranes.

Main Results:

• Formation of a dinitrogen adduct [{K(18-C-6)}2(pyrr2pyr)Fe(N2)] (2) from the starting complex.
• Heterolytic cleavage of benzene C-H bond and fluorobenzene C-F bond by complex 2.
• Successful completion of a synthetic cycle involving C-H activation and borylation, regenerating the active catalyst.

Conclusions:

• The developed method provides an efficient route for benzene C-H activation and borylation.
• This work highlights the potential of potassium-iron complexes in catalytic transformations.
• The synthetic cycle demonstrates a sustainable approach to functionalizing aromatic compounds.