Vanadium hydrides

A 04-003-586B> Tip - Titanium Vanadium S 04-007-8828 VH - Vanadium Hydride C Q4-0O3-2228> TfenVfl2 Titanium Vanadium 0 04-005-6101 TionVoisO Titanium Vanadium Oxide... 

Figure 6. XRD data indicating formation of vanadium hydride on cooling to room temperature under...

H. Yukawa, M. Takagi, A. Teshima, M. Morinaga, Alloying effects on the stabUity of vanadium hydrides, J. Alloys Compd. 330-332 (2002) 105-109. 

The terminal hydrides display a FNb H infrared absorption in the range 1620-1740 cm 1 [falling to 1520-1550 for the (dmpe) compounds], and H-NMR absorption attributable to the hydride ligands in the t range 10.8-17.8. The latter rises to 17-22 for the bridged compounds. Specific data for the compounds are found in Table V. The pattern used in the discussion of the vanadium hydrides is continued, so that the treatment begins with monohydrides and ends with the bridged species. 

The first reported synthesis (9,76) (78%) of Cp2V2(CO)5 (7) involved protonation of the dianion [CpV(CO)3]2- made by sodium amalgam reduction of CpV(CO)4. No vanadium hydride is isolated in this reaction. A slightly better yield (89%) results from the photolysis of CpV(CO)4 in THF using a falling-film photoreactor (77). The product 7 is produced via dimerization of an intermediate solvent complex CpV(CO)3(THF) followed by a further carbonyl loss (35). The corresponding Cp complex 7 is also available by an exactly analogous photolysis of Cp V(CO)4 or by protonation of [Cp V(CO)3]2- (JO). 

For practical applications the important factor is the reversible capacity A H/M) which is defined as the plateau width. Reversible capacity can be considerably less than the maximum capacity (H/ M) max [ 59]. A classic example is vanadium hydride. At 3 5 3 K vanadium forms the so-called monohydride (x 1) at hydrogen pressure... 

The reverse reaction, deprotonation of a vanadium hydride complex to produce an anion, is known. Thus, V(CO)4L2H (L2 = a chelating diphosphine" or diarsine ligand) can be converted to [V(CO)4L2] with OH or NEts. (t -l,3,5-Me3C6H3)V(CO)3H can also be deprotonated with hydroxide ion . 

Inverse Monte Carlo approaches have also been used to extract information from single-crystal diffuse scattering data. For example, effective pair interactions were extracted from vanadium hydride, an important potential hydrogen... 

Bowman, R.C., et al.. Performance testing of a vanadium hydride compressor, Zeitschrift Eur Physikalische Chemie - International Journal of Research in Physical Chemistry Chemical Physics, 1994, 183 p. 245-250. 

Yukawa, H., et al.. Alloying effects on the stability of vanadium hydrides. Journal of alloys and compounds, 2002, 330-332 p. 105-109. 

Chandra, D., et al.. Vanadium Hydrides at Low and High Pressure, Final Report to Tritium Science and Engineering Group, 2006, Los Alamos National Laboratory. Luo, W.R, Clewley, J.D. and Flanagan, T.B., Thermodynamics and isotope effects of the vanadium-hydrogen system using differential heat conduction calorimetry. Journal of Chemical Physics, 1990, 93(9) p. 6710-6722. 

Figure 5.6 Dissociation pressure curves for vanadium hydride VH2. ...

The porcelain tube is slowly heated to, and then held at, a temperature of 900°C until HCl evolution (which follows the initial formation of a small quantity of brown fumes) is complete. After cooling to room temperature (and not before), the product is removed from the reactor in a stream of Hg. At this point, it consists of vanadium hydride (approximate composition VHi.7), which is converted to pure V by heating in high vacuum. It should be borne in mind that finely subdivided vanadium and vanadium hydride are sensitive to atmospheric Og even at room temperature. 

Table 1.1 Bond dissociation energies of some chromium and vanadium hydrides.

---