Magnesium—oxygen bonds

The structures of only a very few heteroleptic monoorganomagnesium compounds with a magnesium-heteroatom bond with heteroatoms other than halogen, oxygen or nitrogen have been determined. 

In aprotic solvents, such as benzene or ether, no protons are available so the concentration of ketyi radical builds up significantly and the ketyi radical anions start to dimerize. As well as being a radical-radical process, this dimerization process is an anion-anion reaction, so why doesn t electrostatic repulsion between the anions prevent them from approaching one another The key to success is to use a metal such as magnesium or aluminium that forms strong, covalent metal-oxygen bonds and that can coordinate to more than one ketyi at once. Once two ketyls are coordinated to the same metal atom, they react rapidly. 

Tossell, J. A. (1977a). A comparison of silicon-oxygen bonding in quartz and magnesium olivine from x-ray spectra and molecular orbital calculations. Amen Mineral. 62, 136-41. 

C. Complexes with Magnesium-Oxygen or Magnesium-Nitrogen Bonds... 

One of the interesting and important aspects of the reaction of dialkylmagnesium compounds with ketones concerns the nature and reactivity of one of the intermediates formed, which contains both a magnesium-oxygen and a magnesium-carbon bond as presented in Scheme 31 ... 

Preparation of an alcohol from an epoxide is shown below. The epoxide (ethylene oxide) ring opens when the nucleophile attacks the carbon-oxygen bond. Note the fact that the nucleophilic carbon is supplied by the Grignard reagent (methyl magnesium bromide). 

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