Organocopper compounds stabilization

Little attention has been paid to the elucidation of the structures of organocopper compounds until recently. The structures of some copper compounds have been determined either by X-ray crystallography or by a combination of NMR and mass spectroscopic data, and the degree of association. Aggregation states have been determined mostly by cry-oscopy, but occasionally by vapor pressure osmometry and ebulliometry where permitted by the stability of the organocopper compound 36, 37, 281f). 

Thermal stabilization of methylcopper by small quantities of magnesium halides has been reported by Costa et al. 82). The stability of ethylcopper is also very dependent on the nature of the magnesium halide present, the iodide having the greatest effect 104). Recent studies indicate that organocopper compounds, RCu, containing metal halides may be cuprates of the type M(RCuX) 190, 191, 257). The presence of... 

Few comparisons have been made among the relative stabilities of other classes of organocopper compounds. Generally, for simple derivatives, the order of decreasing stability is RC=CCu > Aryl-Cu > Alkyl-Cu. For vinylcopper compounds, 2-butenylcopper is more stable than propenylcopper 294). The higher homologs of methylcopper and lithium dimethylcuprate are less stable (69, 276, 297). 

Complexing the unstable organocopper compounds with Tr-bonding ligands fails to confer much additional stability, but several complexes are sufficiently stable to be isolated. It seems best to prepare them from an existing copper(I) complex, e.g. (167),... 

The cuprate complexes have better thermal stability and solubility than the parent organocopper compounds. They can be prepared directly in high yields from the 2 1 reaction of RLi with CuBr [Eqs. (c) -1- (d)] or quantitatively via the 1 1 reaction of... 

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