COMPLEXES OF FEI2 AND FEI3 WITH TETRAMETHYLUREA

[FeI2(OC(NMe2)2)2] (1), [Fe2I4(OC(NMe2)2)2] (2), and [FeI3(OC(NMe2)2] (3) were prepared by the reaction of FeI2 and FeI2/iodine, respectively, with tetramethylurea. The structures of 1 and 3 were determined from single crystal X-ray diffraction data. 1 crystallizes in the triclinic space group P1BAR, with a = 809.9(1), b = 923.2(1), c = 1374.6(l) pm, alpha = 106.80(1), beta = 90.47(1), gamma = 101.55(1)degrees; Z = 2; R = 0.045. 3: monoclinic, P2(1)/c, a = 1311.4(1), b = 783.3(1), c = 1409.1(1)pm, beta = 97.36(1)degrees; Z = 4; R = 0.047. 1 and 3 are isolated neutral complexes with distorted tetrahedral coordination of iron. 3 is the first FeI3-complex with an O-donor ligand. The IR-spectra exhibit strong shifts of nuC=O and nu(as)C-N of tetramethylurea especially on coordinating to FeI3.