Lower-and Higher-order Cyanocuprates

It appeared that [t-BuCu(CN)Li(OEt)2] exists in the solid state as a dimer [t-BuCu(CN)Li(OEt)2]2. Two anionic t-BuCu(CN) units, with almost linear geom- 

NMR investigations [129, 132, 133], EXAFS and XANES studies [134-136], and theoretical calculations [127, 137, 138] performed on higher-order cyanocuprates strongly suggested that the cyanide anion was not bound to copper in these R2Cu(CN)Li2 species. Additional evidence was provided by the first X-ray crystal structure determinations of higher-order cyanocuprates ](C(5H4CH2NMe2-2)2 Cu(CN)Li2] [139] (Fig. 1.34) and [(tBu)2Cu(CN)Li2] [130] (Fig. 1.35). 

On the basis of molecular weight determinations by cryoscopy in THF and conductivity measurements, it was concluded that the polymeric chain breaks up in solution to form smaller aggregates, probably giving rise to solvent-separated 

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