DIVALENT IRON FORMAMIDINATO COMPLEXES - A HIGHLY DISTORTED DINUCLEAR COMPOUND

The reaction of FeCl2 with N,N'-diphenylformamidine, HDPhF, produces the compound FeCl2(HDPhF)2 (I) which upon reaction with methyllithium in Et2O followed by extraction into solvent mixtures containing THF, toluene and hexanes produces crystals of Fe2(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 M2(DPhF)4 or M2(DTolF)4 molecules. The Fe-Fe bond length is 2.462(2) angstrom. Both I and II have been structurally characterized by X-ray crystallography. Crystal data for I at 21-degrees-C are: triclinic, space group P1BAR, a = 10.182(1), b = 11.233(2), c = 13.374(2) angstrom, alpha = 109.87(1), beta = 96.41(1), gamma = 113.35(1)-degrees, Z = 2. For II, the crystal data at -60-degrees-C are: monoclinic, space group I2/a, a = 18.001(6), b = 10.019(1), c = 25.422(9) angstrom, beta = 105.28(1), Z = 4.