Polyiodide amide complexes of transition metals: Structures and raman spectra

The Raman spectra of the polyiodide complexes of d elements with urea (Ur) and acetamide (AA), namely, [M(Ur)6][I3]3 (M = Cr, Fe), Co(Ur)6][I3]2 · 2Ur, [Mn(Ur)6][I8], [Ni(AA)6][I3]2, [M(AA)6][I10 (M = Fe, Co, Cd), and [Co(AA)4(H2O)2][I12], are studied. The structure of [Cr(Ur)6][I3]3 is studied. The crystals of [Cr(Ur)6][I3]3 are monoclinic: space group C2/c, a = 15.260(5), b = 11.941(3), c = 20.506(6) A, β = 106.14(3)°, Z = 4, V = 3589.4(18) A3. The I-I bond length in the CdI2 · 4BA · 2I2 polyiodide complex amorphous to X-rays is estimated by a correlation between the I-I bond length and the frequency of vibrations of this bond in the Raman spectra.