And hydrogen-metal

Trunsition-MetnlHydrides, Tiansition-metal hydiides, ie, inteistitial metal hydrides, have metalhc properties, conduct electricity, and ate less dense than the parent metal. Metal valence electrons are involved in both the hydrogen and metal bonds. Compositions can vary within limits and stoichiometry may not always be a simple numerical proportion. These hydrides are much harder and more brittie than the parent metal, and most have catalytic activity. 

Reaction with Hydrogen and Metals. Bromine combines directiy with hydrogen at elevated temperatures and this is the basis for the commercial production of hydrogen bromide [10036-10-6]. Heated charcoal and finely divided platinum metals are catalysts for the reaction (17). 

M. Ikoma, S. Hamada. N. Morishita, Y. Ho-shina, K. Ohta, T. Kimura, Proc Symp on Hydrogen and Metal Hydride Batteries (Eds. P. D. Bennet, T. Sakai), The electrochemical Society, Pennington, NJ, 1996, 94-27, p. 370. 

At 1400°C and reduced pressure, ZrB2 and HfB2 codeposit with considerable amounts of -rh boron owing to the low vapor pressure of Zr and Hf tetrachlorides. Excess hydrogen and metal tetrachloride are necessary to minimize the formation of uncombined boron. ... 

One of the main concerns for resid HDT catalysts is the life cycle, since it is shorten by the deactivating reactions (formation of ammonia, from HDN coke from poor hydrogenation, and metals accumulation from demetallization, etc.) and the complexity of the... 

The various modes of bonding that have been observed for alkenes to the trinuclear osmium clusters are shown in Fig. 7 [see (88)]. The simple 77-bonded structure (a) is relatively unstable and readily converts to (c) the vinyl intermediate (b) is obtained by interaction of alkene with H2Os3(CO)10 and also readily converts to (c) on warming. Direct reaction of ethylene with Os3(CO)12 produces (c), which is considered to be formed via the sequence (a) — (b) — (c) and (d). Both isomers (c) and (d) are observed and involve metal-hydrogen and metal-carbon bond formation at the expense of carbon-hydrogen bonds. In the reaction of Os3(CO)12 with C2H4, the complex 112088(00)902112, (c), is formed in preference to (d). Acyclic internal olefins also react with the carbonyl, with isomerization, to yield a structure related to (c). Structure (c) is... 

J. A. Martinho Simoes, J. L. Beauchamp. Transition Metal-Hydrogen and Metal-Carbon Bond Strengths The Keys to Catalysis. Chem. Rev. 1990, 90, 629-688. 

Our experiments have shown that hydrogen is critical for growth. The required presence of both hydrogen and metal catalysts, and the virtual absence of silicon vapor suggest that totally new reaction paths assist in the growth of these nanowires under the conditions studied. If silicon does not come directly from the wafer substrate, then it is required to become airborne in some form, as in the CVD production of SiNW, thus enabling tip growth. 

Carbon and hydrogen in coke can be determined by the standard analytical procedures for coal and coke (ASTM D3178, D3179). However, in addition to carbon, hydrogen, and metallic constituents, coke contains considerable amounts of nitrogen and sulfur that must be determined prior to sale or use. These elements will appear as their oxides (NO, SO ), respectively, when the coke is combusted, thereby causing serious environmental issues. 

Dissolving metal reductions were among the first reductions of organic compounds discovered some 130 years ago. Although overshadowed by more universal catalytic hydrogenation and metal hydride reductions, metals are still used for reductions of polar compounds and selective reductions of specific types of bonds and functions. Almost the same results are obtained by electrolytic reduction. 

Besides ring cyclization reactions, reductive methods can also provide access to reduced forms of pyrimidines, quin-azolines, and perimidines. Both hydrogenation and metal hydride addition can be used <1994HC(52)1, 1996HC(55)1>. 

Halogens (7A group elements) have an oxidation state of -1 in their compounds formed with hydrogen and metals. 

Hydrogen and Metal Hydride Batteries, 1994, (Ed. P.D, Bennet and T, Sakai.) Rechargeable Zinc Batteries (Frumkin Symposium), 1995. (Ed. A.J. Salkind,... 

Crystallographic values of metal-hydrogen and metal-oxygen distances in hexaaqua complexes of divalent 3d metal ions compared with calculated effective distances... 

The form of the potential for the system under study was discussed in many publications [28,202,207,208]. Effective pair potentials are widely used in theoretical estimates and numerical calculations. When a many-particle interatomic potential is taken into account, the quantitative description of experimental data improves. For example, the consideration of three-body interactions along with two-particle interactions made it possible to quantitatively describe the stratification curve for interstitial hydrogen in palladium [209]. Let us describe the pair interaction of all the components (hydrogen and metal atoms in the a. and (j phases) by the Lennard Jones potential cpy(ry) = 4 zi [(ff )12- / )6], where Sy and ai are the parameters of the corresponding potentials. All the distances ry, are considered within c.s. of radius r (1 < r < R), where R is the largest radius of the radii of interaction Ry between atoms / and /). 

Insertion of germylenes into metal-halogen, —hydrogen and —metal... 

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