Metallic hydride definition

Proton electroreduction catalyzed by metal complexes is different from reduction at a metal electrode. It definitely involves the formation of metal hydride species through protonation of electroreduced, low-oxidation-state metal complexes that function as Bronsted base (Equation (5)). From protonated... 

Energy Conversion Devices (ECD) of Troy, Michigan has announced a potential breakthrough in solid hydrogen storage. ECD is one of the parent companies of GM Ovonics, patent holder for the nickel metal hydride battery. A hydride, by definition, is a solid material that stores hydrogen. 

An explosion of 1 gm of a hydride thus named, but without more definite identification, during storage in a refrigerator is reported. Such a species might very well evolve either carbon monoxide, or hydrogen, in storage, pressurising its container. See other CARBONYLMETALS, METAL HYDRIDES... 

IV. E.l. The metallic hydrides, such as pentaborane (B5H9), lithium hydride (LiH), and beryllium hydride (BeH2) are attractive candidates if the temperature and pressure of operation fall into a range where evaporation of the metal will occur (48). Such propellants would have a definite advantage over hydrogen in their storability and relatively high densities. 

One remark talks about nano-hydrides become in fashion now. But it is necessary to realize that nearly all the metal hydrides are nano-materials initially, definitely. In the course of hydrogenation, the compact samples of metals (or IMCs) disintegrate into small particles which have (according microscopic or surface-area measurements) micro- (and not nano-) size. However, this does not speak yet for anything. These particles are not monocrystals, but - micro-sized conglomerates of nano-sized clasters (domains). These clasters have sometimes the structure, which differs from that, indicated (defined) by X-ray or neutron... 

In other work cyclic operation of a metal hydride refrigerator [3] was analyzed. With the help of mathematical model for calculation of transfer processes to HHP the algorithm of definition of optimum switching of heat flows in system has been developed at given cycle time. The algorithm is constructed from a condition of achievement of the maximal refrigerating effect (real COP) on unit of brought heat. 

The transition metal hydrides exhibit such wide variations from stoichiometric compositions that they have often been considered interstitial solid solutions of hydrogen in the metal. This implies that the metal lattice has the same structure in the hydride phase as in the pure metal. That this is not the case can be seen in Table I, where of 28 hydrides formed by direct reaction of metal and hydrogen, only three (Ce, Ac, Pd) do not change structure on hydride formation. Even in these three cases, there is a large discontinuous increase in lattice parameter. The change in structure on addition of hydrogen plus the high heats of formation (20 to 50 kcal. per mole) (27) indicates that the transition metal hydrides should be considered definite chemical compounds rather than interstitial solid solutions,... 

Since the transition metal hydrides can be considered definite chemical compounds, it would be more illustrative to derive these expressions from the standpoint of the hydride phase deviating from stoichiometry, rather than the addition... 

In conclusion, the 1,3-dithiane unit still remains among the most valuable acyl anion equivalents, although that involving methyl methylthio sulfoxide or its diethyl analog offers the definite advantages of proceeding with metal hydride or even under phase-transfer catalysis conditions and of producing the carbonyl compound under reasonably mild conditions. 

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