Iron-Catalyzed Selective Hydroboration of CO2 by Cooperative B-H Bond Activation

We report a novel iron(II) complex supported by an anionic phosphanyl-iminopyridinate ligand, Cp*Fe(Cy2PN=C5H4N) (1), which shows remarkable catalytic activity in the selective hydroboration of CO2 with HBpin, producing boryl formate with a turnover frequency (TOF) of similar to 1176 h(-1) at room temperature. This catalysis involves cooperative metal-ligand reactivity for H-B bond activation, affording a key Fe(II)-H intermediate, Cp*FeH(Cy2PN(Bpin)C5H4N) (2), that binds the Bpin moiety at the non-coordinated amino site. The very fast and selective formoxy production can be conveniently coupled to the N-formylation of amines, which delivers a variety of formamides. In addition, the reduction of boryl formate to the CH(3)OBpin stage was also achieved by 1 with HBpin under N-2.

Automated summary

We present a new iron(II) complex with an anionic phosphanyl-iminopyridinate ligand, Cp*Fe(Cy2PN=C5H4N), which demonstrates high catalytic activity in the hydroboration of CO2 with HBpin, yielding boryl formate at a rate of approximately 1176 h(-1) at room temperature. This catalysis involves the cooperative reactivity of the metal-ligand system for H-B bond activation, resulting in the formation of a key Fe(II)-H intermediate, Cp*FeH(Cy2PN(Bpin)C5H4N), which binds the Bpin moiety at the non-coordinated amino site. The rapid and selective production of formic esters can be conveniently coupled with the N-formylation of amines, allowing for the synthesis of various formamides. Additionally, compound 1 also achieves the reduction of boryl formate to CH(3)OBpin stage in the presence of HBpin and N2 gas.