Transition metal dihydrogen chemistry

Ab Initio Studies of Transition Metal Dihydrogen Chemistry... 

Just as bridging hydrides play a central role in the chemistry of Group 13 hydrides, three centre-two electron (3c-2e) bonding is a recurrent fea- Figure 2.17 Polyhydride vs ture of binuclear (and polynuclear) hydrides of the transition metals dihydrogen coordination... 

One of the most interesting aspects of transition metal hydride chemistry is the relationship between this ligand and the rapidly developing chemistry of the dihydrogen ligand, H2. 

The chemistry of transition metal dihydrogen complexes, such as formed in Eq. (1) is in the focus of very intensive studies [13, 14] and such complexes were shown to be involved in the mechanism of several hyrogenation processes [15]. Despite this fact, their role in aqueous-phase hydrogenations is largely unexplored, although examples of water-soluble (or water-stable) dihydrogen complexes are known [16, 17]. Reaction (1) does not involve the change of the oxidation state of... 

Two significant surveys are published in the sane edition of Coordination Chemistry Reviews. Oxygen donor-ligand derivatives of tri-osmium dodecacarbonyl are covered by Frauenhoff and the reactions of transition metal dihydrogen complexes (of which many are carbonyl-containing) are outlined by Jessop and Morris. The crucial role of matrix Isolation studies is well covered in this article. A shorter review of interest here has been published on the role of the phosphorus d-orbitals in M-P bonding. ... 

The study of species in which ethylene is coordinated to transition metal centres holds great interest in areas of catalytic and polymerization chemistry (7). The bonding of the ethylene ligand to the metal centre in such species has been compared to that of the dihydrogen complexes described above (14,15,22). Photolysis of chromium hexacarbonyl, Cr(CO)6, in conventional solvents in the presence of dissolved ethylene gas is known to lead initially to a highly labile species in which one CO ligand is replaced by ethylene. Further photolysis leads to a more stable compound which contains two ethylene ligands trans to each other across the metal centre (25), equation 3. The conventional synthesis is experimentally difficult the two photochemical... 

Asymmetric Synthesis by Homogeneous Catalysis Coordination Chemistry History Coordination Organometallic Chemistry Principles Dihydrogen Complexes Related Sigma Complexes Electron Transfer in Coordination Compounds Electron Transfer Reactions Theory Heterogeneous Catalysis by Metals Hydride Complexes of the Transition Metals Euminescence Luminescence Behavior Photochemistry of Organotransition Metal Compounds Photochemistry of Transition Metal Complexes Ruthenium Organometallic Chemistry. 

Although complexes containing H2 molecules coordinated to transition metals had been proposed for many years, the first structural characterization of a dihydrogen complex did not occur until 1984, when Kubas and coworkers synthesized M(C0)3(PR3)2(H2) (M = Mo, W R = cyclohexyl, isopropyl). Subsequently, many H2 complexes have been identified, and the chemistry of this ligand has developed rapidly. ... 

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