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Andrew J. Peel investigated efficient metalation of unfunctionalized aromatic compounds using mixed copper–lithium amide aggregates. The work connected aggregate composition with exchange behaviour, illustrating why an organometallic reagent's structure in solution can matter to its reactivity.^[ref]

C and the dimer of D have the same composition, $\mathrm{C}{\mathrm{u}}_2\mathrm{L}{\mathrm{i}}_2(\mathrm{TMP}{)}_4$, but different metal ordering around an eight-membered metal–nitrogen ring. C has adjacent Cu sites and adjacent Li sites; in the conventional Gilman dimer D${}_2$, Cu and Li alternate around the four metal positions. D is represented by $\mathrm{Li}[\mathrm{Cu}(\mathrm{TMP}{)}_2]$ per formula unit. The salt by-product is LiCl.

A TMP anion has formula ${\mathrm{C}}_9{\mathrm{H}}_{18}\mathrm{N}$ and mass about 140.25. Therefore the mass per empirical unit is $2(140.25)+63.55+6.94\simeq 350.99$, giving $M_r\simeq 702$ for the dimer, consistent with $699\pm 5$. A monomer would be near 351 and is excluded. In C, inequivalent Cu/Cu, Cu/Li and Li/Li amide surroundings, combined with the constrained TMP orientations, permit the three methyl environments in the observed 1:2:1 integral ratio. D${}_2$ has the higher exchange-averaged methyl equivalence needed for one methyl signal. One signal need not imply that all instantaneous solid-state methyl environments are identical.

The remaining formulae follow from atom and charge balance:E can itself aggregate; its formula here specifies the copper-amide unit. F is a mixed organyl/amido Gilman cuprate, and G combines one F unit with one D unit. The distinct metal-ordering isomers and these mixed aggregates have experimental precedent.^[ref]