Cluster Grignard reagents

Thus, early theoretical and experimental studies of low-temperature reactions in the magnesium-organic halide films allowed one to formulate the problem of obtaining cluster Grignard reagents inaccessible for classical organometallic synthesis but provided no actual evidence of their formation and stabilization. 

Yet another example of catalysis by cluster Grignard reagents is isomerization of alkyl halides. It turned out that, in the presence of these reagents, n-chloroalkanes undergo partial isomerization to produce a mixture of secondary chloroalkanes. The catalytic turnover number is as large as 20. 

What lias been learned relating to die cluster Grignard reagent concept ... 

In all experiments, magnesium vapour has boon co-dcpositcd with an excess of an organic halide RX (R — alkyl, allyl. or aryl X = F, Cl, Br, or I) at 77 K. Aryl halides that are normally unreactive ill classical Grignard reagent preparations react under these conditions. Several cluster Grignard reagents RMg X. n 2 4. have been isolated... 

Thus it appears that cluster Grignard reagents derived from hulobenzenes possess appreciable kinetic stability due to considerable energy barriers to their decomposition. 

Cluster Grignard Reagents—Reactions with Organic Halides 399... 

The implications of this work with respect to elucidating the mechanism of Grignard reagent formation are that small clusters of magnesium may be removed from the surface and that cluster Grignard reagents R Mg)jX may be stable species. 

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