Reviews hydrogen complexes

The work on muonium in Si is distinguished from that on other semiconductors in several respects. Not only was Si the first semiconductor studied, and it is the best understood semiconductor from a muonium point of view, but the importance of hydrogen and hydrogen complexes in Si, to which the muonium studies are relevant, is greatest. Much of the early work on Si predates the new spectroscopic methods described in the previous section. Since most of this early work, along with muon-decay channeling, has been reviewed by Patterson (1988), only the essential points will be included here to put into context the more recent spectroscopic developments. 

D.K. Slattery, M.D. Hampton, Complex hydrides for hydrogen storage, In Proceedings of the 2002 U.S. D.O.E. Hydrogen Program Review NREL/CP-610-32405, Golden, CO. 

Hydrogenation was reviewed recently by Chaloner etal. (85). The history of aqueous metal complex catalysis started with the hydrogenation reaction. Recent work has focused on the search for mechanistic clues to understand the changes in reaction rates and selectivities of aqueous hydrogenation reactions compared with the nonaqueous analogues. 

An early review by Koelle on transition metal catalyzed proton reduction nicely developed the various chemical steps involved in hydrogen evolution including metal hydride formation, hydride acidity (basicity) and protonation and requisite redox potentials.284 The complexes review here have little structural relevance to the hy-drogenase active sites but many show promising catalytic activity. More recently... 

There are a number of reviews available on homogeneous hydrogenation. Specialized reviews are available on hydrogenation with phosphine complexes of rhodium, " on hydrogenation of arenas, on hydrogenation with water-soluble catalysts, " and on mechanistic aspects. There are general reviews covering the older and more recent literature. 

The role of molecular hydrogen complexes in homogeneous catalysis has been reviewed by Oro and Esteruelas and by Bianchini and Peruzzini. The work includes a whole coverage, up to the year 2000, of the literature on transition metal non-classical hydrides, including iridium, which are thought to take part in catalytic reactions. 

Jensen, C., Hydrogen Storage via Polyhidride Complexes, in Proc. 1996 U.S. DOE Hydrogen Program Review, Vol. II (NREL, Golden, CO, 1996), pp. 787-794. 

Since first being discovered in the mid-1980s, molecular hydrogen complexes have been a topic of ever-increasing study. Crabtree s review is an important recent contribution to the field. Several areas of interest within the subject may be delineated. 

Breslow studied the dimerisation of cyclopentadiene and the reaction between substituted maleimides and 9-(hydroxymethyl)anthracene in alcohol-water mixtures. He successfully correlated the rate constant with the solubility of the starting materials for each Diels-Alder reaction. From these relations he estimated the change in solvent accessible surface between initial state and activated complex " . Again, Breslow completely neglects hydrogen bonding interactions, but since he only studied alcohol-water mixtures, the enforced hydrophobic interactions will dominate the behaviour. Recently, also Diels-Alder reactions in dilute salt solutions in aqueous ethanol have been studied and minor rate increases have been observed Lubineau has demonstrated that addition of sugars can induce an extra acceleration of the aqueous Diels-Alder reaction . Also the effect of surfactants on Diels-Alder reactions has been studied. This topic will be extensively reviewed in Chapter 4. 

Other Coordination Complexes. Because carbonate and bicarbonate are commonly found under environmental conditions in water, and because carbonate complexes Pu readily in most oxidation states, Pu carbonato complexes have been studied extensively. The reduction potentials vs the standard hydrogen electrode of Pu(VI)/(V) shifts from 0.916 to 0.33 V and the Pu(IV)/(III) potential shifts from 1.48 to -0.50 V in 1 Tf carbonate. These shifts indicate strong carbonate complexation. Electrochemistry, reaction kinetics, and spectroscopy of plutonium carbonates in solution have been reviewed (113). The solubiUty of Pu(IV) in aqueous carbonate solutions has been measured, and the stabiUty constants of hydroxycarbonato complexes have been calculated (Fig. 6b) (90). 

The clay-cataly2ed iatermolecular condensation of oleic and/or linoleic acid mixtures on a commercial scale produces approximately a 60 40 mixture of dimer acids and higher polycarboxyUc acids) and monomer acids (C g isomerized fatty acids). The polycarboxyUc acid and monomer fractions are usually separated by wiped-film evaporation. The monomer fraction, after hydrogenation, can be fed to a solvent separative process that produces commercial isostearic acid, a complex mixture of saturated fatty acids that is Hquid at 10°C. Dimer acids can be further separated, also by wiped-film evaporation, iato distilled dimer acids and trimer acids. A review of dimerization gives a comprehensive discussion of the subject (10). 

Acid-base interactions in the most general Lewis sense occur whenever an electron pair from one of the participants is shared in the formation of a complex, or an adduct . They include hydrogen bonding as one type of such a bond. The bond may vary from an ionic interaction in one extreme to a covalent bond in the other. Acid-base interactions and their importance in interfacial phenomena have been reviewed extensively elsewhere [35,78] and will be described only briefly here. 

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