Editing Organolithium reagent (section)

===Solution structure===
It is possible for organolithium reagents adopt structures in solution that differ from the solid state.<ref name=Reich /><ref name=solutionenolate>{{cite journal| title = Solution Structures of Lithium Enolates, Phenolates, Carboxylates, and Alkoxides in the Presence of N,N,N′,N′-Tetramethylethylenediamine: A Prevalence of Cyclic Dimers| author = Collum, D. B.| journal = J. Org. Chem.| year = 2008| volume = 73| issue = 19| pages = 7743–7747| doi = 10.1021/jo801532d | pmid = 18781812|display-authors=etal| pmc = 2636848}}</ref> NMR spectroscopy has emerged as a powerful tool for the studies of organolithium aggregates in solution. For alkyllithium species, C−Li ''J'' coupling can often used to determine the number of lithium interacting with a carbanion center, and whether these interactions are static or dynamic.<ref name=Reich /> Separate NMR signals can also differentiate the presence of multiple aggregates from a common monomeric unit.<ref name=reich103>{{cite journal| title = Aggregation and reactivity of phenyllithium solutions| author = Reich, H. J.| journal = J. Am. Chem. Soc.| year = 1998| volume = 120| issue = 29| pages = 7201–7210| doi = 10.1021/ja980684z |display-authors=etal}}</ref>

Organolithium compounds bind [[Lewis base]]s such as [[tetrahydrofuran]] (THF), [[diethyl ether]] (Et<sub>2</sub>O), tetramethylethylene diamine (TMEDA) or [[hexamethylphosphoramide]] (HMPA).<ref name=leadstructure /> [[Methyllithium]] is a special case: its tetrameric structure is unaffected by ether or even HMPA.<ref name=Strohmann /> On the other hand, THF deaggregates hexameric butyl lithium: the tetramer is the main species, and ΔG for interconversion between tetramer and dimer is around 11 kcal/mol.<ref name=McGarrity>{{cite journal| title = High-field proton NMR study of the aggregation and complexation of n-butyllithium in tetrahydrofuran| author = McGarrity, J. F.|author2=Ogle, C.A.| journal = J. Am. Chem. Soc.| year = 1985| volume = 107| issue = 7| pages = 1805–1810| doi = 10.1021/ja00293a001}}</ref> TMEDA can also chelate to the lithium cations in ''n''-butyllithium and form solvated dimers such as [(TMEDA) LiBu-n)]<sub>2</sub>.<ref name=leadstructure /><ref name = Reich /> Phenyllithium has been shown to exist as a distorted tetramer in the crystallized ether solvate, and as a mixture of dimer and tetramer in ether solution.<ref name =Reich />

{| border="1" class="wikitable"  style="text-align:center; margin-left: auto; margin-right: auto; border: none;"
|+ Solvated alkyllithium aggregate structures<ref name=Reich />
! Alkyl group
! Solvent
! Structure
|-
| rowspan=2 | methyl || THF || tetramer
|-
| ether/HMPA || tetramer
|-
| rowspan=3 | ''n''{{nbh}}butyl || pentane || hexamer
|-
| ether || tetramer
|-
| THF || tetramer-dimer
|-
| ''sec''{{nbh}}butyl || pentane || hexamer-tetramer
|-
| isopropyl || pentane || hexamer-tetramer
|-
| rowspan=2 | ''tert''{{nbh}}butyl || pentane || tetramer
|-
| THF || monomer
|-
| rowspan=2 | phenyl || ether || tetramer-dimer
|-
| ether/HMPA || dimer
|}