Divalent iron formamidinato complexes: a highly distorted dinuclear compound

Abstract

The reaction of FeCl 2 with N, N′-diphenylformamidine, HDPhF, produces the compound FeCl 2(HDPhF) 2 ( I) which upon reaction with methyllithium in Et 2O followed by extraction into solvent mixtures containing THF, toluene and hexanes produces crystals of Fe 2(DPhF) 4 ( II). This dinuclear compound contains four formamidinato bridges but in an arrangement that is highly distorted compared to the previously known structures of M 2(DPhF) 4 or M 2(DTolF) 4 molecules. The FeFe bond length is 2.462(2) Å. Both I and II have been structurally characterized by X-ray crystallography. Crystal data for I at 21 °C are: triclinic, space group P 1 , a = 10.182(1), b = 11.233(2), c = 13.374(2) Å, α = 109.87(1), β = 96.41(1), γ = 113.35(1)°, Z = 2. For II, the crystal data at −60 °C are: monoclinic, space group I2/ a, a = 18.001(6), b = 10.019(1), c = 25.422(9) Å, β = 105.28(1), Z = 4.