Trinuclear fragments as nucleation centres: New polyoxoalkoxyvanadates by (induced) self-assembly

Müller A, Meyer J, Bögge H, Stammler A, Botar A. Trinuclear fragments as nucleation centres: New polyoxoalkoxyvanadates by (induced) self-assembly. CHEMISTRY-A EUROPEAN JOURNAL. 1998;4(8):1388-1397.The presence of pentaerythritol (C(CH2OH)(4)) in an aqueous vanadate solution leads-depending on the pH value and other specific reaction conditions-to the formation of (CN3H6)(4)Na-2 [(H4V6P4O30)-P-IV{(CH2)(3)-CCH2OH2]. 14H(2)O (1), Na-6[(H4V6P4O30)-P-IV{(CH2)(3)CCH2OH}(2)]. 18 H2O (2), (NH4)(7)[(H7V12V7O50)-V-IV-O-V (CH2)(3)CCH2OH]. 11.5 H2O . (3), (CN3H6)(4)[(V3V4O19F)-V-IV-O-V(CH2)(3)CCH2OH] . 5.25 H2O (4), Na-6[(V10V2O30F2)-V-IV-O-V{(CH2)(3)CCH2OH}(2)]. 22- H2O (5) or (CN3H6)(4)[(V2V8O28F2)-V-IV-O-V-{(CH2)(3)CCH2OH}(2)] . 4 H2O (6). The corresponding anions contain as basic structural elements trinuclear {V3O13} or {V3O12F} units, which are stabilized by the organic substituent acting as a tripod ligand. It can be assumed in principle that these units act as nucleation centres during the formation processes of the cluster anions. In this context it is remarkable that the trinuclear units can even occur in a quasi-isolated state, as in the anions of 1 and 4, The compounds were characterized by IR, UV/Vis/NIR and EPR spectroscopy as well as by magnetochemical investigations and single-crystal X-ray structure determinations. Susceptibility data are especially useful for identifying the trinuclear units as well as the nature of their magnetic coupling with the rest of the structure