Editing Gilman reagent (section)

==Structure==
Lithium dimethylcuprate exists as a [[Dimer (chemistry)|dimer]] in [[diethyl ether]] forming an 8-membered ring. Similarly, lithium diphenylcuprate crystallizes as a dimeric etherate, {{chem2|[{Li(OEt2)}(CuPh2)]2}}.<ref>{{cite journal | journal = [[Angewandte Chemie|Angew. Chem. Int. Ed.]] | volume = 29 | issue = 3 | pages = 300–302 | year = 1990 |author1=N. P. Lorenzen |author2=E. Weiss | doi = 10.1002/anie.199003001 | title = Synthesis and Structure of a Dimeric Lithium Diphenylcuprate:[{Li(OEt)<sub>2</sub>}(CuPh<sub>2</sub>)]<sub>2</sub>}}</ref>

<div class="center">[[File:Lithium-diphenylcuprate-dietherate-dimer-from-xtal-3D-sticks-C.png|200px|Lithium diphenylcuprate etherate dimer from crystal structure - 3D stick model]] [[File:Lithium-diphenylcuprate-etherate-dimer-from-xtal-2D-skeletal.png|180px|Skeletal formula of lithium diphenylcuprate etherate dimer]]</div>

If the Li<sup>+</sup> ions is complexed with the [[crown ether]] [[12-crown-4]], the resulting diorganylcuprate anions adopt a linear [[coordination geometry]] at copper.<ref>{{ cite journal | journal = [[Journal of the American Chemical Society]] | title = Isolation and x-ray crystal structures of the mononuclear cuprates [CuMe<sub>2</sub>]<sup>−</sup>, [CuPh<sub>2</sub>]<sup>−</sup>, and [Cu(Br)CH(SiMe<sub>3</sub>)<sub>2</sub>]<sup>−</sup> |author1=H. Hope |author2=M. M. Olmstead |author3=P. P. Power |author4=J. Sandell |author5=X. Xu | year = 1985 | volume = 107 | issue = 14 | pages = 4337–4338 | doi = 10.1021/ja00300a047| bibcode = 1985JAChS.107.4337H }}</ref>

<div class="center">[[File:Dimethylcuprate-anion-from-xtal-3D-balls.png|100px|Dimethylcuprate anion from crystal structure]] [[File:Diphenylcuprate-anion-from-xtal-3D-balls.png|220px|Diphenylcuprate anion from crystal structure]]</div>

For the 'higher order cyanocuprate' Li<sub>2</sub>CuCN(CH<sub>3</sub>)<sub>2</sub>, Lipshutz and coworkers have claimed that the cyanide ligand is coordinated to Li and π-bound to Cu.<ref>{{cite journal|author=Bruce H. Lipshutz; Brian James|title=New 1H and 13C NMR Spectral Data on "Higher Order" Cyanocuprates. If the Cyano Ligand Is Not On Copper, Then Where Is It?|journal=J. Org. Chem.|year=1994|volume=59 |issue=25 |pages=7585–7587|doi=10.1021/jo00104a009}}</ref>  However, the existence of 'mixed higher order organocuprates' has been disputed by Bertz and coworkers, who rejoined that the cyano ligand is actually bound solely to the lithium atom, and that such a structure could still explain the enhanced reactivity of cuprate prepared from CuCN.<ref>{{Cite journal |last=Bertz |first=Steven H. |last2=Miao |first2=Guobin |last3=Eriksson |first3=Magnus |date=1996-01-01 |title=It's on lithium! an answer to the recent communication which asked the question: ‘if the cyano ligand is not on copper, then where is it?’ |url=https://pubs.rsc.org/en/content/articlelanding/1996/cc/cc9960000815 |journal=Chemical Communications |language=en |issue=7 |pages=815–816 |doi=10.1039/CC9960000815 |issn=1364-548X|url-access=subscription }}</ref><ref>{{Cite web |last=Bertz |first=Steven H. |date=2002-05-01 |title=New copper chemistry. 17. Higher-order cyanocuprates: are they real? |url=https://pubs.acs.org/doi/pdf/10.1021/ja00166a046 |access-date=2025-04-18 |website=ACS Publications |language=EN |doi=10.1021/ja00166a046}}</ref> To date, no crystallographic evidence for the existence of 'mixed higher order cuprates' ([R<sub>2</sub>CuX]<sup>2–</sup>, X ≠ R) has been obtained.  On the other hand, a homoleptic higher order cuprate in the form of a [Ph<sub>3</sub>Cu]<sup>2–</sup> moiety has been observed in Li<sub>3</sub>Cu<sub>2</sub>Ph<sub>5</sub>(SMe<sub>2</sub>)<sub>4</sub>, prepared by Olmstead and Power.<ref>{{Cite journal |last=Olmstead |first=Marilyn M. |last2=Power |first2=Philip P. |date=1989-05-01 |title=Structural characterization of a higher order cuprate: x-ray crystal structure of [Li3Cu2Ph5(SMe2)4] |url=https://pubs.acs.org/doi/10.1021/ja00193a075 |journal=Journal of the American Chemical Society |volume=111 |issue=11 |pages=4135–4136 |doi=10.1021/ja00193a075 |issn=0002-7863|url-access=subscription }}</ref>