Structural elucidation of tmeda-solvated alkali metal diphenylamide complexes

Alan R. Kennedy, Jan Klett, Charles T. O'Hara, Robert E. Mulvey, Gemma M. Robertson

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Lithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X-ray crystallography) and solution(by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co-ligand N,N,N,N-tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)- M(NPh2)}2] (M = Li for 1, Na for 2) can be prepared by treating 1 mol.-equiv. of the parent amine with an equimolar quantity of nBuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four-atom M-N-M-N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda)3/2K(NPh2)}2] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been Alkali metal amides and their solvates are continuing to attract a great deal of interest due to their use in alkali metal/hydrogen exchange reactions.[1-5] In particular, the metal salts of diisopropylamine [da(H)], 1,1,1,3,3,3-hexamethyldisilazane [hmds(H)] and 2,2,6,6-tetramethylpiperidine [tmp(H)] are widely utilised across synthetic laboratories primarily because of the desirable combination of high Brønsted basicity and low nucleophilicity. Of particular interest in this study, another amido reagent, the thermally highly stable lithium diphenylamide (LiNPh2), has shown promise in a range of synthetic transformations. As well as regioselective deprotonation reactions,[6-10] it has also been used in catalytic aldol reactions involving silyl enol ethers and aldehydes;[11,12] in elimination applications;[13,14] in metathetical reactions;[15-27] during the preparation of amino-containing carbenes,[28] and as an initiator in the polymerisation of methyl methacrylate.[29]
LanguageEnglish
Pages5029-5035
Number of pages7
JournalEuropean Journal of Inorganic Chemistry
Volume2009
Issue number33
DOIs
Publication statusPublished - Nov 2009

Fingerprint

Alkali Metals
Metal complexes
Lithium
Atoms
Salts
Metals
Diphenylamine
Deprotonation
Ethers
Methacrylates
X ray crystallography
Hexanes
Alkalinity
Aldehydes
Amides
Amines
Hydrogen
Potassium
Sodium
Polymerization

Keywords

  • alkali metals
  • amides
  • N ligands
  • NMR spectroscopy
  • structure elucidation

Cite this

@article{d67a61d89b214a7eaef5ef55410cf8be,
title = "Structural elucidation of tmeda-solvated alkali metal diphenylamide complexes",
abstract = "Lithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X-ray crystallography) and solution(by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co-ligand N,N,N,N-tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)- M(NPh2)}2] (M = Li for 1, Na for 2) can be prepared by treating 1 mol.-equiv. of the parent amine with an equimolar quantity of nBuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four-atom M-N-M-N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda)3/2K(NPh2)}2] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been Alkali metal amides and their solvates are continuing to attract a great deal of interest due to their use in alkali metal/hydrogen exchange reactions.[1-5] In particular, the metal salts of diisopropylamine [da(H)], 1,1,1,3,3,3-hexamethyldisilazane [hmds(H)] and 2,2,6,6-tetramethylpiperidine [tmp(H)] are widely utilised across synthetic laboratories primarily because of the desirable combination of high Br{\o}nsted basicity and low nucleophilicity. Of particular interest in this study, another amido reagent, the thermally highly stable lithium diphenylamide (LiNPh2), has shown promise in a range of synthetic transformations. As well as regioselective deprotonation reactions,[6-10] it has also been used in catalytic aldol reactions involving silyl enol ethers and aldehydes;[11,12] in elimination applications;[13,14] in metathetical reactions;[15-27] during the preparation of amino-containing carbenes,[28] and as an initiator in the polymerisation of methyl methacrylate.[29]",
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author = "Kennedy, {Alan R.} and Jan Klett and O'Hara, {Charles T.} and Mulvey, {Robert E.} and Robertson, {Gemma M.}",
year = "2009",
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Structural elucidation of tmeda-solvated alkali metal diphenylamide complexes. / Kennedy, Alan R.; Klett, Jan; O'Hara, Charles T.; Mulvey, Robert E.; Robertson, Gemma M.

In: European Journal of Inorganic Chemistry, Vol. 2009, No. 33, 11.2009, p. 5029-5035.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Structural elucidation of tmeda-solvated alkali metal diphenylamide complexes

AU - Kennedy, Alan R.

AU - Klett, Jan

AU - O'Hara, Charles T.

AU - Mulvey, Robert E.

AU - Robertson, Gemma M.

PY - 2009/11

Y1 - 2009/11

N2 - Lithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X-ray crystallography) and solution(by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co-ligand N,N,N,N-tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)- M(NPh2)}2] (M = Li for 1, Na for 2) can be prepared by treating 1 mol.-equiv. of the parent amine with an equimolar quantity of nBuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four-atom M-N-M-N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda)3/2K(NPh2)}2] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been Alkali metal amides and their solvates are continuing to attract a great deal of interest due to their use in alkali metal/hydrogen exchange reactions.[1-5] In particular, the metal salts of diisopropylamine [da(H)], 1,1,1,3,3,3-hexamethyldisilazane [hmds(H)] and 2,2,6,6-tetramethylpiperidine [tmp(H)] are widely utilised across synthetic laboratories primarily because of the desirable combination of high Brønsted basicity and low nucleophilicity. Of particular interest in this study, another amido reagent, the thermally highly stable lithium diphenylamide (LiNPh2), has shown promise in a range of synthetic transformations. As well as regioselective deprotonation reactions,[6-10] it has also been used in catalytic aldol reactions involving silyl enol ethers and aldehydes;[11,12] in elimination applications;[13,14] in metathetical reactions;[15-27] during the preparation of amino-containing carbenes,[28] and as an initiator in the polymerisation of methyl methacrylate.[29]

AB - Lithium, sodium and potassium salts of diphenylamine have been prepared by using a deprotonative route and characterised in both, solid state (by X-ray crystallography) and solution(by NMR spectroscopic studies). In each case the metal atom's coordination sphere is completed by coordination to the synthetically important co-ligand N,N,N,N-tetramethylethylenediamine (tmeda). Complexes 1 and 2 [{(tmeda)- M(NPh2)}2] (M = Li for 1, Na for 2) can be prepared by treating 1 mol.-equiv. of the parent amine with an equimolar quantity of nBuM and tmeda in hexane solution. In the solid state, 1 and 2 are essentially isostructural, being dimeric with a four-atom M-N-M-N framework. The coordination sphere of each M atom is completed by a bidentate tmeda molecule. Complex 3 [{(tmeda)3/2K(NPh2)}2] has been prepared in a similar way to 1 and 2 except that benzylpotassium has been Alkali metal amides and their solvates are continuing to attract a great deal of interest due to their use in alkali metal/hydrogen exchange reactions.[1-5] In particular, the metal salts of diisopropylamine [da(H)], 1,1,1,3,3,3-hexamethyldisilazane [hmds(H)] and 2,2,6,6-tetramethylpiperidine [tmp(H)] are widely utilised across synthetic laboratories primarily because of the desirable combination of high Brønsted basicity and low nucleophilicity. Of particular interest in this study, another amido reagent, the thermally highly stable lithium diphenylamide (LiNPh2), has shown promise in a range of synthetic transformations. As well as regioselective deprotonation reactions,[6-10] it has also been used in catalytic aldol reactions involving silyl enol ethers and aldehydes;[11,12] in elimination applications;[13,14] in metathetical reactions;[15-27] during the preparation of amino-containing carbenes,[28] and as an initiator in the polymerisation of methyl methacrylate.[29]

KW - alkali metals

KW - amides

KW - N ligands

KW - NMR spectroscopy

KW - structure elucidation

U2 - 10.1002/ejic.200900782

DO - 10.1002/ejic.200900782

M3 - Article

VL - 2009

SP - 5029

EP - 5035

JO - European Journal of Inorganic Chemistry

T2 - European Journal of Inorganic Chemistry

JF - European Journal of Inorganic Chemistry

SN - 1434-1948

IS - 33

ER -