B-hydrides

Fig. 11. X-ray diffraction pattern of a Ni99Cul alloy partially transformed into its (3-hydride (0 NiCuH) before (a) and after (b) hydride decomposition. Arrows point to the diffraction peaks representing the rich in copper alloy phsae desegregated from the initial alloy after a multiple hydrogen absorption-desorption treatment. After Palczew-ska and Majchrzak (48).

Hydrozirconation of iminoboranes -B=N-R leads to a four-membered ring with a Zr-H-B hydride bridge [209]. 

Carbonylation is an exceedingly broad subject, but the main reaction patterns can be easily rationalized by recalling the classification used earlier for coupling reactions involving (a) metallacycles (b) hydride-promoted reactions and (c) oxidative addition of organic halides to zero-valent nickel. In fact, one or other of these steps is necessary to form a species able to undergo carbonylation. 

Two significant items were confirmed in this work (a) Molybdenum, and most probably tungsten, can expand its sphere of coordination beyond 6 and (b) hydride shifts transforming olefins to allyls or 7r-allyls, via v -> (t and 77 - Tj3 processes, respectively, are feasible in metals that are known to produce active metathesis catalysts. 

In the case of hydrogenation using [Ru(BINAP)Cl2]n as the catalyst precursor, the reaction seems to occur by a monohydride mechanism as shown in Scheme 6-31. On exposure to hydrogen, RuC12 loses chloride to form RuHCl species A, which in turn reversibly forms the keto ester complex B. Hydride transfer occurs in B from the Ru center to the coordinated ketone to form C. The reaction of D with hydrogen completes the catalytic cycle.67... 

Figure 1. a. cw-enediol mediated isomerization (36,37) b. hydride shift mechanism... 

Hydrides. Both ionic covalent compounds of H with another element usually metallic. These will generally be described under the other element eg Al-hydride in Vol 1, p A145 B-hydrides in Vol 2, pp B253-56. However certain... 

B. Hydrides AHa.—HeH has been investigated at SCF level, using a CGTO basis set. The ground-state PE surface was computed in this work.378... 

First b-hydride elimination occurs with the formation of (c), and then migratory insertion results in the formation of (d). Elimination of the acetaldehyde and a hydrogen ion then leaves Pd (0). The Pd (0) is converted back to Pd(II) by the auxiliary Cu(II)-catalysed air oxidation. 

For the analysis influence of design weight on COP we shall present (13) in the simplified kind, assuming, that the heat capacity of hydride and a material of a design of a sorber is approximately identical both weights low-temperature A and high-temperature B hydride are equal ... 

Figure 6.7 (Below) Metal-mediated alkene isomerization via (a) allyl or (b) hydride intermediates...

Hammes-Schiffer, S. Watney, J. B. Hydride transfer catalysed by Escherichia coli and Bacillus subtilis dihydrofolate reductase coupled motions and distal mntations, Philos. Trans. R. Soc. London Ser. B 2006, 361, 1365-1373. 

Ans. (a) Hydrogen ion (b) Hydride ion (c) Sodium hydride (d) Beryllium hydride... 

Scheme 23. (a) Cycloaddition and (b) hydride-transfer pathways via -promoted ET from BNAH... 

Figure 2. (a) Addition-Elimination (A-E) and (b) Hydride-Transfer (H-T) methanol electro-oxidation mechanisms by Methanol Dehydrogenase Enzyme proposed in the literature. 

Key to method (A) exchange reaction with tin heterocycle (B) hydride addition to diyne (C) oxidation of saturated ketone (D) bromination-dehydrobromination by pyrolysis (E) reaction of RLi or ArLi with exocyclic M-Cl of preformed diene (F) ring expansion reaction from cyclopentadiene derivative (G) LiAlHi reduction of exocyclic M-Cl (H) carbene insertion into five-membered cyclo-pentadiene derivative. Doering-Hoffman method (I) 1,6-cycloaddition of GeCU. 

Kalina, D. G., Marks, T. J. Wachter, W. A. "Photochemical Synthesis of Low-Valent Organothorium Complexes. Evidence for Photoinduced B-Hydride Elimination," J. Amer. Chem. 

This reaction followed by three further steps, namely (a) a fast hydrogen transfer from the (S-carbon of the chain to the metal, (b) hydride transfer... 

In Section 8C -1. we considered methods for introducing solution samples b hydride genetiilion, Aioniiza-li()fi of the hydrides requires only thai they be healed in a quartz lube, as shtwvn in Figure... 

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