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 ∼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 CH3OBpin stage was also achieved by 1 with HBpin under N2.