Strukturelle und spektroskopische Charakterisierung sechsfach koordinierter Vanadium(V)-Komplexe: Ein Strukturmodell für das aktive Zentrum Vanadium-abhängiger Haloperoxidasen

Structural and Spectroscopic Characterization of Six-Coordinate Vanadium(V) Complexes: A Structural Model for the Active Site of Vanadium-Dependent Haloperoxidases A series of vanadium(V) complexes has been synthesized from ammonium metavanadate and trivalent, pentadentate Schiff base ligands. These aliphatic as well as aromatic hydroxyl groups containing ligands are stabilizing the VO³⁺ unit. The complexes 1–5 are characterized by ¹H-, ¹³C- and ⁵¹V-NMR, virbrational (IR, Raman and resonance Raman) and electronic spectroscopy as well as EHMO calculations. The X-ray crystal structure analysis of 1 (monoclinic space group P2₁/n: a = 1 073.3(2); b = 1 201.1(3); c = 1 165.7(3) pm; β = 101.89(2)°; Z = 4) shows that the vanadium(V) center has a distorded octahedral environment. The LMCT transition of the complexes 1–5 in the electronic spectra has been observed at comparatively high energies (21.8 ? 25.8 × 10³ cm^?1) and are assigned based on resonance Raman spectra and EHMO calculations. The implications of the observed physical properties of the complexes 1–5 to the structural model proposed for the active site of vanadat(V)-dependent haloperoxidases are discussed.     

Ein ungewöhnlicher ambivalenter Zinn(II)‐oxo‐Cluster

An Unusual Ambivalent Tin(II)‐oxo Cluster The reaction of the copper aryl CuDmp (Dmp = 2, 6‐Mes₂C₆H₃; Mes = 2, 4, 6‐Me₃C₆H₂) with the stannanediyl Sn{1, 2‐(tBuCH₂N)₂C₆H₄} followed by hydrolysis affords in the presence of lithium‐tert‐butoxide the tin(II)‐oxo cluster {(Et₂O)(LiOtBu)(SnO)(CuDmp)}₂ ( 5 ) in small yield. The solid state structure of the colorless compound shows a central Li₂Sn₂O₂(OtBu)₂ fragment with heterocubane structure. In addition, the Li‐acceptor and O(Sn)‐donor atoms are used for the coordination of one molecule diethylether and copper aryl CuDmp, respectively.     

NO2−-Komplexe von Kupfer(II) mit ungewöhnlicher Koordination

NO₂^? Complexes of Copper(II) with Unusual Coordination The structures and spectroscopic properties of various new alkali nitro(nitrito) complexes of copper(II) are reported. Cs₄KCu₃(NO₂)_11-x(OH)_x (OH₂) [x ≈ 1] crystallizes in a cubic perovskite-analogous structure with a square-planar coordination of Cu²⁺ by the nitrogen ligator atoms, which is considerably disordered, however. The K⁺ substitution by a further Cs⁺ cation leads to a monoclinic distortion of the unit cell. The Cu(NO₂)₅^3? polyhedra in the compound Cs₃Cu(NO₂)₅, which is also of the perovskite-type with respect to the metal ion positions, are (distorted) axially compressed trigonal bipyramids. The groundstate is predominantly d — as expected. The NO₂- anions are partly nitro- and partly nitrito-bonded to Cu²⁺ and additionally disordered with respect to this bonding isomerism in the equatorial plane. Further compounds of the two structural types with different alkali cations were prepared.