Ternary hydrides

Ternary hydrides of Rh and Ir containing the octahedral anions have been... 

In the Li-Rh system LiRh is prepared from rhodium metal foil and liq Li in a 25 at% excess of the 1 1 molar ratio. The mixture is heated in an iron crucible to 750-880°C in Ar. The direct reaction of the elements in a molybdenum crucible at 800°C for 7 d produces LiRh. Identical methods produce Lilr and Lilrj with which the rhodium compounds are isostructural . The reaction of Rh metal with LiH at 600°C gives the ternary hydrides Li4RhH4 and Li4RhH5. 

Bronger, W. and G. Auffermann, New ternary alkali-metal-transition-metal hydrides synthesized at high pressures Characterization and properties, Chem. Mater., 10, 2723,1998. 

The reduction of 7,8-dihydrofolate (H2F) to 5,6,7,8-tetrahydrofolate (H4F) has been analyzed extensively14 26-30 and a kinetic scheme for E. Coli DHFR was proposed in which the steady-state kinetic parameters as well as the full time course kinetics under a variety of substrate concentrations and pHs were determined. From these studies, the pKa of Asp27 is 6.5 in the ternary complex between the enzyme, the cofactor NADPH and the substrate dihydrofolate. The second observation is that, contrary to earlier results,27 the rate determining step involves dissociation of the product from the enzyme, rather than hydride ion transfer from the cofactor to the substrate. 

Figure 10. The ternary complex of the enzyme dihydrofolate reductase, the substrate and the cofactor during the transition state of the hydride ion transfer. The enzyme backbone atoms are shown alone for clarity and are colored blue. The substrate is shown in yellow and the cofactor is in red. The bond colored in light blue indicates the hydride ion being shared by both the cofactor and the substrate before the transfer to the substrate. Water molecules around the residue pteridine of the substrate and the nicotinamide ring of the cofactor alone are shown and colored in light blue. The yellow spheres represent the sodium ions and the pink spheres the chloride ions.

Nowotny el al. (1956) who initially thought that all these phases were ternaries (Me5X3Z) According to Corbett and Leon-Escamilla (2003) the preparation of a hydrogen-free compound and of a ternary hydride can be summarized by the following reaction examples ... 

The next alkali earth in the periodic table is Ca and its ternary hydride was found to be less stable than the Mg ternary hydride. Indeed, the desired reaction for CaNij is ... 

Early Studies of Noninterstitial Transition Metal Ternary Hydrides... 

Guenee et al. [169] synthesized by ingot metallurgy ternary intermetallic compounds LaNi Mg and NdNi Mg having the cubic MgCu Sn crystal structure. They can absorb reversibly up to four hydrogen atoms per formula unit at 7-8 bar and 50°C. The hydrides are stable at room temperature but desorb quite rapidly at 80°C in vacuum. In air, they decompose by catalytic water formation. 

K Yvon, B. BertheviUe, Magnesium based ternary metal hydrides containing alkali and alkaline-earth elements, J. Alloys Compd. 425 (2006) 101-108. 

N. Hanada, S. Orimo, H. Fujii, Hydriding properties of ordered-/disordered-Mg-based ternary Laves phase structures, J. Alloys Compd. 356-357 (2003) 429-432. 

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