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The reaction involves no changes in the oxidation state of the metal and can be viewed as splitting H 2 into hydride (which binds to the metal) and proton (which binds to the base). ML n x+ + base + H 2 ⇌ HML n (x-1)+ + Hbase + Such reaction are assumed to involve the intermediacy of dihydrogen complexes. Bifunctional catalysts activate H 2 ...
Classical transition metal hydride feature a single bond between the hydrogen centre and the transition metal. Some transition metal hydrides are acidic, e.g., HCo(CO) 4 and H 2 Fe(CO) 4. The anions potassium nonahydridorhenate [ReH 9] 2− and [FeH 6] 4− are examples from the growing collection of known molecular homoleptic metal hydrides. [16]
In general, complex metal hydrides have the formula M x M' y H n, where M is an alkali metal cation or cation complex and M' is a metal or metalloid.Well known examples feature group 13 elements, especially boron and aluminium including sodium aluminium hydride, NaAlH 4), lithium aluminium hydride, LiAlH 4, and lithium borohydride, (LiBH 4).
The reaction is driven by the thermodynamic properties of the intermediates and the products. Several other mechanisms have been proposed for this reaction, including a radical mechanism as well as a mechanism involving an aluminium hydride species. The commonly accepted direct hydride transfer is supported by experimental and theoretical data. [6]
More exotic transfer hydrogenations have been reported, including this intramolecular one: Transfer hydrogenation. Many reactions exist with alcohol or amines as the proton donors, and alkali metals as electron donors. Of continuing value is the sodium metal-mediated Birch reduction of arenes (another name for aromatic hydrocarbons).
Many reactions in organometallic chemistry involve insertion of one ligand (L) into a metal-hydride or metal-alkyl/aryl bond. Generally it is the hydride, alkyl, or aryl group that migrates onto L, which is often CO, an alkene, or alkyne.
The reverse of olefin insertion into a metal-hydrogen bond is β-hydride elimination. The Principle of Microscopic Reversibility requires that the mechanism of β-hydride elimination follow the same pathway as the insertion of alkenes into metal hydride bonds. The first requirement for β-hydride elimination is the presence of a hydrogen at a ...
The hydrogen atoms occupy interstitial sites in palladium hydride. The H–H bond in H 2 is cleaved. The ratio in which H is absorbed on Pd is defined by = [] [].When Pd is brought into a H 2 environment with a pressure of 1 atm, the resulting concentration of H reaches x ≈ 0.7.