Vanadium magnetic susceptibility

These dimeric complexes involve, in their neutral state, two metal atoms in the (III) oxidation state. In the vanadium complexes such as [CpV(bdt)]2 and [CpV(tft)]2, the V—V bond length, 2.54 A in [CpV(bdt)]2, are shorter than observed in model complexes with a single V—V bond, indicating a partial double-bond character, also confirmed by a measured magnetic moment of 0.6 fiB in [CpV(tfd)]2, lower than expected if the two remaining unpaired electrons contribute to the magnetic susceptibility [20, 49]. This class of complexes most probably deserves deeper attention in order to understand their exact electronic structure. 

The structures of the anhydrous vanadiumfiii) sulphates, 2(804)3, yellow (monoclinic) and green (rhombohedral), have been investigated, and a new double sulphate, (NH4)3V(S04)3, has been prepared and extensively characterized. Single-crystal magnetic susceptibility studies (1.5—20 K) of guanidi-nium vanadium(iii) sulphate have been reported, and the zero-field splitting has been estimated as 3.74 cm . ... 

Figure 6.19 Magnetic susceptibility of vanadium sulphides as a function of temperature and composition. (After De Vries Haas, 1973.)...

Some properties of selected vanadium compounds are listed in Table 1. Detailed solubility data are available (3), as are physical constants of other vanadium compounds (4). Included are the lattice energy of several metavanadates and the magnetic susceptibility of vanadium bromides, chlorides, fluorides, oxides, and sulfides (5). 

Two techniques capable of positive identification of both the vanadyl and the vanadium(III) oxidation states are extended X-ray absorption spectroscopy (EXAS) and magnetic susceptibility. EXAS experiments on A. ceratodes yield approximately 95% V(III) and 5% V(IV) (148). A similar distribution, 90% V(III) and 10% V(IV), was found for A. nigra using a superconducting quantum interference device to measure magnetic susceptibility (149). 

More complicated aggregate structures are found in the vanadium-copper and vanadium-silver species [ViMiS SPh CR ]" (M = Cu or Ag) (133), in which the metal sulfido core is in the shape of a cube [Fig. 14(d)] bulk magnetic susceptibility measurements have shown that there is probably a direct V —V bond within these species. These and related complexes are of interest since a vanadium-containing nitrogenase has been discovered (136). 

Oxides. TijOa has been investigated by X-ray spectroscopy and by e.p.r. spectroscopy and magnetic susceptibility measurements - there has been an improved MO calculation of its band structure. A band model has been proposed to account for the origin of the magnetic moment and metallic transition of vanadium-doped Ti203- According to e.p.r. measurements the Ti ions in mixed valence phases of the system Ti 0 mined. 

Vanadium(ill).—Halides and Oxyhalides. Magnetic susceptibilities have been obtained for MVF4, M2VF5, M2VFj,H20, and MVF4(H202) (M = NH4, K, Rb, or Cs) over the temperature range 78.5—290 and also for p-K VFj (0.45 < x <... 

Magnetic susceptibility measurements of two of the synthesized compositions strongly suggest, that the majority oxidation state of vanadium in these NASICON phases is The respective measured values are 1.57 BM for NbVP30i2 and 2.13 BM for SbVP30i2. Additional measurements, including XPS are necessary to more exactly define the oxidation state of the vanadium. 

Fig. 27. Temperature dependence of the magnetic susceptibility of CsV205. The curve in the dashed line deals with a pair of exchange-coupled vanadium (IV) ions...

Magnetic susceptibility measurement on a Boscan (SR) vanadium petroporphyrin extract indicates Curie-Weiss dependence. V-V interaction or... 

Vanadium(IV) oxide, VO2, is prepared by heating V2O5 with H2C2O4. It crystallizes with a rutile-type structure (Figure 6.21) which is distorted at 298 K so that pairs of V(IV) centres are alternately 262 and 317 pm apart the shorter distance is consistent with metal-metal bonding. This polymorph is an insulator, but above 343 K, the electrical conductivity and magnetic susceptibility of VO2 increase as the regular rutile structure is adopted. Vana-dium(IV) oxide is blue but shows thermochromic behaviour... 

The mixture of TCNE and hexacarbonyl vanadium(O) in an organic solvent yields an organic-based magnet with the highest critical temperature to date - ca. 400 K (Eq. 9). However, the detailed solid-state structure of this compound has not been determined due to its air/water reactivity, amorphous morphology, and solvent insolubility. The entrapped solvent is at least partially responsible for its air sensitivity and magnetic susceptibility. That is, CVD of V[TCNE] in the absence of... 

G.D. Khattak, A. Mekki, L.E. Wenger, X-ray photoelectron spectroscopy (XPS) and magnetic susceptibility studies of vanadium phosphate glasses. J. Non-Cryst. Solids 355(43 4), 2148-2155 (2009)... 

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