Expanding the Reactivity of Masked Divalent Lanthanide–Isocarbonyl Complexes

High Resolution Image Download MS PowerPoint Slide Masked divalent reactivity is a potentially powerful strategy for accessing the reducing chemistry of lanthanides without the need to isolate unstable divalent lanthanide compounds. Here, we report the synthesis and characterization of the isocarbonyl-bridged complexes [(Cp*) 2 Gd(THF)(μ-Fp)] ∞ ( 1 Gd ) and [(Cp*) 2 Lu(μ-Fp)] 2 ( 1 Lu ) (Fp = CpFe(CO) 2 ), aiming to extend the masked divalent approach to gadolinium and lutetium, metals with very limited divalent chemistry. Structural studies show that 1 Gd forms as a coordination polymer with nine-coordinate gadolinium centers, whereas 1 Lu is a dimer with eight-coordinate lutetium, reflecting the influence of the lanthanide contraction. FTIR spectroscopy confirms strong isocarbonyl back-bonding in both compounds. Complexes 1 M (M = Gd, Dy, Lu) react with phenazine to afford dimetallic phenazine-bridged products [{(Cp*) 2 M} 2 (μ-phnz)] ( 2 M ), demonstrating two-electron reduction of an N -heterocyclic substrate by the isocarbonyl-bridged complexes. Magnetic measurements reveal extremely weak antiferromagnetic exchange in 1 Gd and 2 Gd, while the dysprosium analogue exhibits slow magnetic relaxation governed by Raman and quantum tunnelling processes. These results establish isocarbonyl-bridged lanthanide metallocenes as platforms for ligand-based reduction chemistry involving metals with very limited divalent chemistry.