Oxovanadium(IV)-sulfite compounds: Synthesis and structural and physical studies
(EN)
Chilas, G. I.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Chilas, G. I.
(EN)
Reaction of VIVOCl2 in strongly acidic aqueous solution with either (NH4)(2)SO3 or Na2SO3 and Bu4NBr at similar to 70 degrees C in the pH range 2.5-4.5 gives the clusters (NH4)(2){[V-4(IV)(mu(4)-O)(2)(mu(3)-OH)(2)]((VO)-O-IV)(2)(mu(3)-SO3)(4)O-4(H2O)(2)} and (n-Bu4N)(2){[V-4(IV)(mu(4)-O)(2)(mu(3)-OH)(2)]((VO)-O-IV)(2)(mu(3)-SO3)(4)O-4(H2O)(2)}, respectively. Reaction of (NH4VO3)-O-V with (NH4)(2)SO3 resulted in the isolation of the first compound. When the latter reaction is carried out in the presence of MgO, compound (NH4)[(VO)-O-IV(SO3)(1.5)H2O](infinity)center dot 2.5H(2)O was isolated instead. Compound (n-Bu4N)(2){[V-4(IV)(mu(4)-O)(2)(mu(3)-OH)(2)]((VO)-O-IV)(2)(mu(3)-SO3)(4)O-4(H2O)(2)} and (NH4)[(VO)-O-IV(SO3)(1.5)H2O](infinity)center dot 2.5H(2)O were characterized by X-ray structure analysis. The crystal structure of species (n-Bu4N)(2){IV4IV(mu(4)-O)(2)(mu(3)-OH)(2)]((VO)-O-IV)(2)(mu(3)-SO3)(4)O-4(H2O)(2)} revealed a unprecedented hexanuclear cluster consisting of a cubane core [M-4(mu(4)-O)(2)(mu(3)- OH)(2)] connected to two other metal atoms through the core oxo-groups and four mu(3)-SO3 bridges. Compound (NH4)[VIVO(SO3)(1.5)H2O](infinity)center dot 2.5H(2)O represents a rare example of an open-framework species prepared under mild conditions. Cyclic voltammetric examination of compound (n-Bu4N)(2){[IV4IV(mu(4)-O)(2)(mu(3)-OH)(2)]((VO)-O-IV)(2)(mu(3)-SO3)(4)O-4(H2O)(2)] revealed a redox process which was assigned to the oxidation of one core of vanadium(IV) to vanadium(V).
(EN)
