Oxidative addition hydrogen molecule

Ca.ta.lysis, Iridium compounds do not have industrial appHcations as catalysts. However, these compounds have been studied to model fundamental catalytic steps (174), such as substrate binding of unsaturated molecules and dioxygen oxidative addition of hydrogen, alkyl haHdes, and the carbon—hydrogen bond reductive elimination and important metal-centered transformations such as carbonylation, -elimination, CO reduction, and... 

In the alkanethiol case, the reaction may be considered formally as an oxidative addition of the S—H bond to the gold surface, followed by a reductive elimination of the hydrogen. When a clean gold surface is used, the proton probably ends as a molecule. Monolayers can be formed from the gas phase (241,255,256), in the complete absence of oxygen ... 

RhCl(PPh3)3 is a very active homogenous hydrogenation catalyst, because of its readiness to engage in oxidative addition reactions with molecules like H2, forming Rh—H bonds of moderate strength that can subsequently be broken to allow hydride transfer to the alkene substrate. A further factor is the lability of the bulky triphenylphosphines that creates coordinative unsaturation necessary to bind the substrate molecules [44]. 

Investigation of direct conversion of methane to transportation fiiels has been an ongoing effort at PETC for over 10 years. One of our current areas of research is the conversion of methane to methanol, under mild conditions, using li t, water, and a semiconductor photocatalyst. Research in our laboratory is directed toward ad ting the chemistry developed for photolysis of water to that of methane conversion. The reaction sequence of interest uses visible light, a doped tungsten oxide photocatalyst and an electron transfer molecule to produce a hydroxyl i cal. Hydroxyl t cal can then react with a methane molecule to produce a methyl radical. In the preferred reaction pathway, the methyl radical then reacts with an additional wata- molecule to produce methanol and hydrogen. 

As shown earlier, Co(CN)53 has the ability to split hydrogen molecules as a result of an oxidative addition reaction. 

The first step in this process is an oxidative addition that is followed by a hydrogen transfer to a coordinated ethene molecule to convert it to an ethyl group. The third step involves the addition of a ligand as the C2H4 molecule undergoes an insertion reaction to give a coordinated butyl group. 

The reactions of MeOH with some transition metal oxide cluster anions [M O J, where M = Mn, Fe, Co, Ni, Cu n = 1,2 x = 2—4, have been studied (254). The [M03] anions were unreactive toward MeOH, unlike [Nb03]. The addition of the hydrogen molecule to the other cluster anions was the common reaction yielding the following transformations,... 

As briefly discussed in section 1.1, and shown in Figure 1, the accepted mechanism for the catalytic cycle of hydrogenation of C02 to formic add starts with the insertion of C02 into a metal-hydride bond. Then, there are two possible continuations. The first possibility is the reductive elimination of formic acid followed by the oxidative addition of dihydrogen molecule to the metal center. The second possible path goes through the a-bond metathesis of a metal formate complex with a dihydrogen molecule. In this section, we will review theoretical investigations on each of these elementary processes, with the exception of oxidative addition of H2 to the metal center, which has already been discussed in many reviews. 

Addition of molecules across unsaturated organic bonds is an extremely important process that includes reactions such as hydrogenation, hydroformylation, oxidation, hydrocyanation, hydrosilylation and many others. These reactions are often most effectively catalysed by homogeneous catalysts and in this chapter we will focus on hydrogenation (addition of H2) and hydroformylation (addition of H2 and CO), which are shown generically in Scheme 8.1. 

During the chemisorptions of Ru3(CO)i2 or Os3(CO)i2 on silica, the first step with the surface silanols was to produce a covalent bonding with the silica surface by oxidative addition of the silanol group to the metal-metal bond of the clusters. The nature of surface molecular species [=Si-0)(M3( x-H)(CO)io)j covalently linked to the silica surface (M = Ru, Os) was clearly defined and structurally characterized by a series of physical and chemical techniques, including mass balance taking into account the evolution of two molecules of CO and one molecule of hydrogen [27, 33, 35]. 

The second point relates to this as well as to your observation that the abstraction of hydrogen from water molecules is assisted by coordination of the water, particularly with Fe+2. The mechanism of ferrous oxidation by hydrogen atom has been a controversial question, and several mechanisms have been proposed. Among them are one suggested by Jortner, Czapski, Stein, and myself involving the addition of hydrogen atoms to the ferrous ion to form a hydrido iron complex analagous to CuH+—i.e.,... 

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