Organometallic reactivity studies

The ionization potential in a simple one-electron approximation measures the energy of the highest occupied molecular orbital (HOMO). This orbital is only one of an entire manifold of levels which contribute to the bonding characteristics and total stability of the cluster. Frontier fragment-orbital analysis in organometallic reactivity studies has provided a clear indication... 

Convenient Pressure Reactors for Organometallic Reactivity Studies... 

ESI represents a powerful method by which to transfer organometallic ions from catalytically active solutions into the gas phase. ESI-MS systems allow the characterization of the gas-phase ions using CID, reactivity, and isotope-labeling studies. The application of ESI-tandem-MS systems allows gas-phase preparations and isolation of desired organometallic ions in the first ESI-octopole-quad-rupole, followed by characterization or reactivity studies in the second octopole-quadrupole. 

It is apparent from the above discussions that recent synthetic, structural, bonding, and reactivity studies have established transition metal containing metallacarborane complexes as an important area of study in organometallic chemistry. 

Industrially this diene is made the same way as ethylidenenorbomene from butadiene and ethene, but now isomerisation to 2,4-hexadiene should be prevented as the polymerisation should concern the terminal alkene only. In both systems nickel or titanium hydride species react with the more reactive diene first, then undergo ethene insertion followed by (3-hydride elimination. Both diene products are useful as the diene component in EPDM rubbers (ethene, propene, diene). The nickel hydride chemistry with butadiene represents one of the early examples of organometallic reactions studied in great detail [22] (Figure 9.14). 

The use of bulky monodentate m-terphenyl ligands in the stabilisation of d-block organometallic compounds is surveyed. Importantly, these ligands have facilitated the isolation of hitherto unknown species containing low-coordinate centres and metal-metal multiple bonds. This review reports on these advances with emphasis on the synthesis, structural characterisation and, where possible, reactivity studies of complexes featuring metal-carbon bonds between m-terphenyl ligands and the transition metals. 

Sun, J.L., Berg, D.J., and Twamley, B. (2008) Yttrium complexes of a phenanthrene-fused cyclopentadienyl synthetic, structural, and reactivity studies. Organometallics, 27, 683. 

The second case study we wish to describe concerns the photochemistry of Fe(CO)s. How spin states affect organometallic reactivity is a fundamental question that is key to many areas of inorganic chemistry, and Fe(CO)s is a... 

Gruber, S. Neuburger, M. Pfaltz, A. Characterization and reactivity studies of dinuclear iridium hydride complexes prepared from iridium catalysts with N, P and C, N ligands under hydrogenation conditions. Organometallics 2013,32,4702-4711. 

Dedieu A, Bo C, Ingold F (1990) Theoretical studies on carbon dioxide organometallic reactivity. In Aresta M, Schloss JV (eds) Enzymatic and model reactions for carbon dioxide utilization. Kluwer, Dordrecht, pp 23-42... 

But, is a continuum representation of solvent always sufficient May we neglect specific solute-solvent interactions such as H-bonds And what about reactions in which the solvent plays the role of a reactant Furthermore, do species in solution interact, e.g., a charged catalyst with its counterion, and how would this affect the catalyst s reactivity To address these and similar questions, we first have to extend the model systems considered to include an explicit representation of solvent and of those molecular species which may have an impact on reactivity. A first step in this direction is the use of cluster-continuum models in which a reduced number of explicit solvent molecules are introduced in the model. This approach has been successfully applied in computational studies of the organometallic reactivity [12-14], yet it suffers from some limitations [15]. How many solvent molecules should be explicitly included Is the first solvation sphere enough In order to mimic bulk conditicHis, models have to include enough solvent molecules to fully solvate the solute. These models, which are built to reproduce experimental densities, are generally treated as periodically repeating units in order to remove the explicit/ continuum (or vacuum) boundary. 

In addition to these applications the nucleophilicity of calcium-based organometallics can be exploited in stoichiometric reactions. The enormous reactivity toward weak acids justifies cmisideration of these reagents as superbases [49] with the tendency to degrade ethers as a characteristic feature. Due to the fact that two recent and excellent review articles already focus on catalytic applications [132, 133] we limit the discussion on selected stoichiometric reactivity studies. 

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