Département de chimie moléculaire

{Hydrothermal reaction of Na2WO4, VOSO4, 2,2'-bpy and H3PO4 has afforded in high yield [VIV2VV6O14(bpy)8(PO4)2][PW11VVO40](bpy)·12H2O (1). Compd. 1 contains a novel octanuclear mixed valence V(iv,v) cluster, [VIV2VV6O14(bpy)8(PO4)2]4+, with [PW11VVO40]4- as counterion. In the V cluster, four V(V) centers are localized and the remaining two V(IV) and two V(V) ions are disordered over four crystallog. equiv. positions. Isostructural [VIV2VV6O14(bpy)8(PO4)2][PMo11VVO40](bpy)·3H2O (2) also was synthesized. Thermodiffractometry expts. indicate that 2 is stable up to 360°. Redox activities for both the V and Mo centers were obsd. by solid-state electrochem. measurements performed on mech. attached microparticles of 2. Magnetic measurements performed on 1 showed the occurrence of weak ferromagnetic interactions between the V(IV) centers (J = +0.34 cm-1