Organometallic complexes transition state structure

DFT calculations on the Mg(L—H)+ complex also reveal how HNCO might be lost (Scheme 10). Thus the bidentate interaction of the acetamide ligand with Mg in 51 must be disrupted to yield either of the monodentate structures 52 or 54. These intermediates can insert into the CH3—C bond via four-centered transition states to yield the organometallic ions 53 or 55, which can then lose HNCO to form MgCH3+. The DFT calculations reveal that path (A) of Scheme 10 is kinetically favored. 

Organometallic compounds asymmetric catalysis, 11, 255 chiral auxiliaries, 266 enantioselectivity, 255 see also specific compounds Organozinc chemistry, 260 amino alcohols, 261, 355 chirality amplification, 273 efficiency origins, 273 ligand acceleration, 260 molecular structures, 276 reaction mechanism, 269 transition state models, 264 turnover-limiting step, 271 Orthohydroxylation, naphthol, 230 Osmium, olefin dihydroxylation, 150 Oxametallacycle intermediates, 150, 152 Oxazaborolidines, 134 Oxazoline, 356 Oxidation amines, 155 olefins, 137, 150 reduction, 5 sulfides, 155 Oxidative addition, 5 amine isomerization, 111 hydrogen molecule, 16 Oxidative dimerization, chiral phenols, 287 Oximes, borane reduction, 135 Oxindole alkylation, 338 Oxiranes, enantioselective synthesis, 137, 289, 326, 333, 349, 361 Oxonium polymerization, 332 Oxo process, 162 Oxovanadium complexes, 220 Oxygenation, C—H bonds, 149... 

Also, metal ion directed stereoselective syntheses often involve organometallic complexes. While there is no fundamental difference between metal-carbon and metal-heteroatom bonds, modeling rc-bonded ligands is not trivial.1 Given a known reaction mechanism (which is not possible for many catalytic reactions), the main problem is the parameterization of the potential energy functions for the intermediates and transition states. The problem is that force field parameters are generally carefully fitted to experimental results, i.e., structures or other data related to the output of force field calculations of the type of compound to be modeled have to be available. For short-lived transition states this is a considerable problem. 

Asymmetric Synthesis by Homogeneous Catalysis Carbonylation Processes by Homogeneous Catalysis Coordination Organometallic Chemistry Principles Electronic Structure of Clusters Hydride Complexes of the Transition Metals Hydrides Solid State Transition Metal Complexes Organic Synthesis using Transition Metal Complexes Containing jr-Bonded Ligands Oxidation... 

The changes in structure during this attack are depicted in Equation 11.21. Eisenstein and Hoffmann concluded many years ago that a symmetric metal-olefin complex is deactivated toward nucleophilic attack, but slippage of the olefin creates a LUMO that can interact with the incoming nucleophile. Thus, in the transition state for external attack, "the organometallic olefinic complex cannot be near its equilibrium structure." ... 

R.D. Simpson, R.G. Bergman - Synthesis, Structure, and Exchange-Reactions of Rhenium Alkoxide and Aryloxide Complexes. Evidence for Both Proton and H-Atom Transfer in the Exchange Transition State, Organometallics 12,781,1993. 

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