28276-08-6Relevant articles and documents
COMPLEXES OF IMIDAZOLE LIGANDS
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Page/Page column 82, (2012/01/05)
Metal imidazolate complexes are described where imidazoles ligands functionalized with bulky groups and their anionic counterpart, i.e., imidazolates are described. Compounds comprising one or more such polyalkylated imidazolate anions coordinated to a metal or more than one metal, selected from the group consisting of alkali metals, transition metals, lanthanide metals, actinide metals, main group metals, including the chalcogenides, are contemplated. Alternatively, multiple different imidazole anions, in addition to other different anions, can be coordinated to metals to make new complexes. The synthesis of novel compounds and their use to form thin metal containing films is also contemplated.
Absolute kinetic rate constants and activation energies for the formation of Grignard reagents
Beals, Bridget J.,Bello, Zainab I.,Cuddihy, Kathleen P.,Healy, Ethan M.,Koon-Church, Stephanie E.,Owens, Jane M.,Teerlinck, Cynthia E.,Bowyer, Walter J.
, p. 498 - 503 (2007/10/03)
This paper reports the first absolute rate constants for the formation of Grignard reagents from magnesium metal and organohalides. The theory that allows calculation of heterogeneous rate constants from the rate of growth of individual pits is described. By monitoring the reaction of individual reactive sites on the magnesium surface using photomicrography, it is possible to determine the rate of reaction and the active surface area; rate constants then are calculated from those data. Rate constants are on the order of 10-4 cm/s and vary relatively little between various organohalides. By measuring rate constants over a range of temperatures, Arrhenius parameters are determined for the reaction. The magnitudes of the enthalpic and entropic barriers are not consistent with electron transfer as the rate-limiting step. Rather, the data suggest that the rate-limiting step is reaction of the organohalide at the magnesium surface with partial insertion of a magnesium atom into the carbon-halide bond in the transition state.
