PUB - Publikationen an der Universität Bielefeld

Polyoxovanadates with distorted Lindquist-structure, in which six of the twelve mu(2)-oxygen atoms are formally replaced by the oxygen atoms of two coordinated pentaerythritol ligands, can be prepared by a simple method in an aqueous medium. The ''fully reduced'', six-fold protonated compound cis-(Na2V6O7)-O-V(OH)(6){(OCH2)(3)CCH2OH}(2)]. 8H(2)O (1), the mixed valence species cis-(CN3H6)(3)[(VV5O13)-V-IV-O-V{[(OCH2)(3)CCH2OH}(2)]. 4.5H(2)O (2) containing one localized V-IV centre and the ''fully oxidized'' compound trans-(CN3H6)(2)[(V6O13)-O-V{(OCH2)(3)CCH2 . OH}(2)]. H2O (3) have been synthesized and characterized by UV/VIS-, IR- and EPR-spectroscopy, by magnetic measurements, cyclic voltammetry and by a single-crystal X-ray structure analysis. The organic {(CH2)(3)CCH2OH}(3+)-groups tend to cap the triangular faces formed by mu(2)-oxygen atoms of the central approximately octahedral {V6O19}-unit. Therefore the anions of bis-(trisalkoxy)-hexavanadates can exist in a trans-form as well as in an isomeric cis-form referring to a ''basic'' plane of four vanadium atoms of the [V-6]-octahedron. The different relative positions of the ligands have a significant influence on the redox potentials of the compounds. For structural details see ''Inhaltsiibersicht''.