Synthesis and Characterization of (catecholato)bis(β-diketonato)vanadium(iv) Complexes

The syntheses of the complexes [V(cat)(acac)], [V(cat)(bzac)], and [V(dtbc)(bzac)] are described, and the complexes' UV-visible, infrared, and mass spectral data are presented. The complexes are nonelectrolytes with a room-temperature magnetic moment of about 1.8 μb, consistent with the dvanadium(IV) system. The complexes show reversible one-electron reduction to the vanadium(III) state at -0.22, -0.26, and -0.37 V (NHE), respectively, in acetonitrile and at -0.39, -0.38, and -0.56 V (NHE), respectively, in dichloromethane. Oxidation to the vanadium(V) state does not occur at potentials less positive than 1.0 V, at which the catecholate ligands undergo oxidation. These mixed-ligand vanadium(IV) complexes are more stable to disproportionation than the tris(catecholato) and tris(β-diketonato) complexes, more stable to oxidation than the former complexes, and more stable to reduction than the latter

Synthetic, Structural, and Physical Studies of Tris(2,4-pentanedionato)vanadium(IV) Hexachloroantimonate(V) and Tris(l-phenyl-l,3-butanedionato)vanadium(IV) Hexachloroantimonate(V)

The complexes [V(acac)][SbCl] (1) and [V(bzac)] [SbCl]-CHCl(2) have been prepared by reaction of [V(acac)Cl] and [V(bzac)Cl], respectively, with SbClin acetic acid solution. Their crystal structures are described. Crystals of 1 are orthorhombic, space group Pcab, with a = 14.167 (9) A, b =18.774 (3) A, c = 19.670 (6) A, Z = 8, and R= 3.3%. Crystals of 2 are triclinic, space group P1, with a = 12.070 (6) A, b = 14.110 (4) A,c = 15.792 (2) A, a = 66.46 (2)°, β = 69.08 (2)°, ϒ = 65.90 (2)°, Z = 2, and R= 5.6%. The geometry about vanadium in each structure approximates octahedral with trigonal twist angles of 51.9 and 52.3°, respectively. The chelate rings are not planar, with two chelate rings in each complex possessing boat conformations. Corresponding hexafluorophosphates were also prepared. The results of optical and infrared spectroscopy, magnetic susceptibility, conductance, and electrochemical studies are reported

Polyoxovanadium(IV) sulfite compounds: Synthesis, structural, and physical studies

An unexplored family of polyoxometalates has evolved through the synthesis and structural characterization of vanadium(IV) sulfite heteropolyanions. The hexanuclear vanadium(IV) compound, which is ferromagnetic down to 2 K, exhibits a unique structural motif for such metal species, with a central cubic {M<sub>4</sub>O<sub>2</sub>(OH)<sub>2</sub>} fragment and metal centers at two of the corners of the cluster

A novel series of vanadium-sulfite polyoxometalates: synthesis, structural, and physical studies

Reaction of NH4VO3 with sulfur dioxide affords the hexanuclear cluster (NH4)(2)(Et4N)((VO)-O-IV)(6)(mu(4)-O)(2)(mu(3)-OH)(2)(mu(3)-SO3)(4)(H 2O)(2)]Cl center dot H2O (1), and the decapentanuclear host-guest compound (Et4N)(5){Cl subset of(VO)(15)(mu(3)-O)(18)(mu-O)(3)]}center dot 3H(2)O (2). Sequential addition of magnesium oxide to an acidic aqueous solution of NH4VO3 (pH approximate to 0) followed by (NH4)(2)SO3 resulted in the formation of either the non-oxo polymeric vanadium(IV) compound trans-(NH4)(2)V-IV(OH)(2)(mu-SO3)(2)] (3) or the polymeric oxovanadium(IV) sulfite (NH4)(VO)-O-IV-(SO3)(1.5)(H2O)]center dot 2.5 H2O (4) at pH values of 6 and 4, respectively. The decameric vanadium(v) compound {Na-4(mu-H2O)(8)(H2O)(6)} Mg(H2O)(6)]V-10(V)(O)(8)(mu(6)-O)(2)(mu(3)-O)(14)]center dot 3H(2)O (5) was synthesised by treating an acidic aqueous solution of NH4VO3 with MgO and addition of NaOH to pH approximate to 6. All the compounds were characterised by single-crystal Xray structure analysis. The crystal structure of compound I revealed an unprecedented structural motif of a cubane unit M-4(mu(4)-O)(2)(mu 3-OH)(2)] connected to two other metal atoms. Compound 3 comprises a rare example of a non-oxo vanadium(IV) species isolated from aqueous solution and in the presence of the reducing agent SO32-, while compound 4 represents a rare example of an open-framework species isolated at room temperature (20 degrees C). In addition to the synthesis and crystallographic studies, we report the IR and magnetic properties (for 1, 2 and 3) of these vanadium clusters as well as theoretical studies on compound 3

Novel compound with a 1D network structure constructed by ((VO)-O-IV)(6)(mu(4)-O)(2)(mu(3)-OH)(2)(mu(3)-SO3)(4)](2-)/SO32- and 4,4 `-bipyridine components: its synthesis, characterization, and magnetic behavior

The organically templated compound (NH4)(3)(4,4'-Hbpy)((VO)-O-IV)(6)(mu(4)-O)(2)(mu(3)-OH)(2)(mu-SO3)(4) (mu-SO3)]center dot 15/2 H2O 1 is the first example of an extended structure in which a polyoxometalate anion, (H2V6S4O22)-S-IV-O-IV](2-), is linked by the pyramidal mu(2)-bridging sulfite group forming a linear polymeric {V-6}(eta) chain. Two such chains are linked into a `double-rung ladder' assembly via two different hydrogen bonds provided by 4,4'-Hbpy(+) cations

A novel polyoxo(thio)molybdenum(V) sulfite compound: Synthesis and crystal structure of {Mo-2(V)(mu-S)(2)O-2](6)(mu(3)-SO3)(4)(mu-SO3)(12)}(20-)anion

The non-cyclic polyoxo(thio) molybdate(V)-sulfite K-6(NH4)(14){Mo-2(V)(mu-S)(2)O-2](6)(mu(3)-SO3)(4)(mu-SO3)(12)} . 7H(2)O 1 was prepared by self-condensation of Mo-2(V)(mu-S)(2)O-2](2+) building block in the presence of (NH4)(2)SO3. Compound 1 was characterized by X-ray structure analysis as well as IR, UV-vis spectroscopies and thermogravimetric analysis

Oxovanadium(IV)-sulfite compounds: Synthesis and structural and physical studies

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)-SO 3)(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)-SO 3)(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)

Solution identification and solid state characterisation of a heterometallic polyoxometalate {Mo(11)V(7)}: Mo(11)(VI)V(5)(V) V(2)(IV)O(52)(mu(9)-SO(3))](7-)

A polyoxomolybdenum/vanadium-sulfite {M(18)} cluster-based compound, Mo(11)(VI)V(5)(V)V(2)(IV)O(52)(mu(9)-SO(3))](7-), is reported that exhibits a unique structural motif, arising from the incorporation of five V(V) and two V(IV) ions into a {M(18)} cluster framework templated by SO(3)(2-); this cluster compostion was first identified using cryospray mass spectrometry