High-field lithium-7 nuclear magnetic resonance spectroscopic and cryoscopic relative molecular mass studies on solutions of amido- and imido-lithium compounds

D REED, D BARR, Robert Mulvey, R SNAITH

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Abstract

High-field lithium-7 n.m.r. spectroscopy and molecular mass measurements are shown to provide an important guideline into the nature of the species present in benzene and toluene solutions of a representative selection of amido- and imido-lithium derivatives. The compounds have solid-state structures ranging from hexameric to tetrameric clusters {[Ph(But)CNLi]6(3), [(Me2N)2CNLi]6(4), [Ph(Me2N)CNLi]6(5), to (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine)}, to trimeric and dimeric rings {[(PhCH2)2NLi]3(6) and (But2CNLi·hmpa)2(1)(hmpa = hexamethylphosphoramide), [(PhCH2)2NLi·OEt3]2(7), with probably n= 2 for [PhN(H)Li·hmpa]n(8), and [(C6H11)2NLi·hmpa]n(10)}, and to a likely monomer {[(Bun)(C5H5N)Li·2(NC5H8)]n(9)}, yet even more diverse behaviour has been detected in solution. Thus while some of the compounds essentially retain their solid association states [hexameric (3), (4), (5), dimeric (8), and monomeric (9)], others engage in concentration-dependent equilibria also involving monomeric species [tetrameric (2), trimeric (6), dimeric (1) and (10)], and one complex [dimeric (7)] loses donor on dissolution before rearranging to a trimer and a monomer.
LanguageEnglish
Pages557-564
Number of pages8
JournalJournal of the Chemical Society, Dalton Transactions
Issue number3
DOIs
Publication statusPublished - Mar 1986

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Lithium Compounds
Molecular mass
Lithium
Monomers
Hempa
Nuclear magnetic resonance
Toluene
Benzene
Dissolution
Spectroscopy
Derivatives

Keywords

  • magnetic resonance
  • imido-lithium compounds
  • spectroscopy

Cite this

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title = "High-field lithium-7 nuclear magnetic resonance spectroscopic and cryoscopic relative molecular mass studies on solutions of amido- and imido-lithium compounds",
abstract = "High-field lithium-7 n.m.r. spectroscopy and molecular mass measurements are shown to provide an important guideline into the nature of the species present in benzene and toluene solutions of a representative selection of amido- and imido-lithium derivatives. The compounds have solid-state structures ranging from hexameric to tetrameric clusters {[Ph(But)CNLi]6(3), [(Me2N)2CNLi]6(4), [Ph(Me2N)CNLi]6(5), to (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine)}, to trimeric and dimeric rings {[(PhCH2)2NLi]3(6) and (But2CNLi·hmpa)2(1)(hmpa = hexamethylphosphoramide), [(PhCH2)2NLi·OEt3]2(7), with probably n= 2 for [PhN(H)Li·hmpa]n(8), and [(C6H11)2NLi·hmpa]n(10)}, and to a likely monomer {[(Bun)(C5H5N)Li·2(NC5H8)]n(9)}, yet even more diverse behaviour has been detected in solution. Thus while some of the compounds essentially retain their solid association states [hexameric (3), (4), (5), dimeric (8), and monomeric (9)], others engage in concentration-dependent equilibria also involving monomeric species [tetrameric (2), trimeric (6), dimeric (1) and (10)], and one complex [dimeric (7)] loses donor on dissolution before rearranging to a trimer and a monomer.",
keywords = "magnetic resonance , imido-lithium compounds , spectroscopy",
author = "D REED and D BARR and Robert Mulvey and R SNAITH",
year = "1986",
month = "3",
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T1 - High-field lithium-7 nuclear magnetic resonance spectroscopic and cryoscopic relative molecular mass studies on solutions of amido- and imido-lithium compounds

AU - REED, D

AU - BARR, D

AU - Mulvey, Robert

AU - SNAITH, R

PY - 1986/3

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N2 - High-field lithium-7 n.m.r. spectroscopy and molecular mass measurements are shown to provide an important guideline into the nature of the species present in benzene and toluene solutions of a representative selection of amido- and imido-lithium derivatives. The compounds have solid-state structures ranging from hexameric to tetrameric clusters {[Ph(But)CNLi]6(3), [(Me2N)2CNLi]6(4), [Ph(Me2N)CNLi]6(5), to (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine)}, to trimeric and dimeric rings {[(PhCH2)2NLi]3(6) and (But2CNLi·hmpa)2(1)(hmpa = hexamethylphosphoramide), [(PhCH2)2NLi·OEt3]2(7), with probably n= 2 for [PhN(H)Li·hmpa]n(8), and [(C6H11)2NLi·hmpa]n(10)}, and to a likely monomer {[(Bun)(C5H5N)Li·2(NC5H8)]n(9)}, yet even more diverse behaviour has been detected in solution. Thus while some of the compounds essentially retain their solid association states [hexameric (3), (4), (5), dimeric (8), and monomeric (9)], others engage in concentration-dependent equilibria also involving monomeric species [tetrameric (2), trimeric (6), dimeric (1) and (10)], and one complex [dimeric (7)] loses donor on dissolution before rearranging to a trimer and a monomer.

AB - High-field lithium-7 n.m.r. spectroscopy and molecular mass measurements are shown to provide an important guideline into the nature of the species present in benzene and toluene solutions of a representative selection of amido- and imido-lithium derivatives. The compounds have solid-state structures ranging from hexameric to tetrameric clusters {[Ph(But)CNLi]6(3), [(Me2N)2CNLi]6(4), [Ph(Me2N)CNLi]6(5), to (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine)}, to trimeric and dimeric rings {[(PhCH2)2NLi]3(6) and (But2CNLi·hmpa)2(1)(hmpa = hexamethylphosphoramide), [(PhCH2)2NLi·OEt3]2(7), with probably n= 2 for [PhN(H)Li·hmpa]n(8), and [(C6H11)2NLi·hmpa]n(10)}, and to a likely monomer {[(Bun)(C5H5N)Li·2(NC5H8)]n(9)}, yet even more diverse behaviour has been detected in solution. Thus while some of the compounds essentially retain their solid association states [hexameric (3), (4), (5), dimeric (8), and monomeric (9)], others engage in concentration-dependent equilibria also involving monomeric species [tetrameric (2), trimeric (6), dimeric (1) and (10)], and one complex [dimeric (7)] loses donor on dissolution before rearranging to a trimer and a monomer.

KW - magnetic resonance

KW - imido-lithium compounds

KW - spectroscopy

U2 - 10.1039/DT9860000557

DO - 10.1039/DT9860000557

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JO - Journal of the Chemical Society, Dalton Transactions

T2 - Journal of the Chemical Society, Dalton Transactions

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