Synthesis and characterization of new mixed-metal sodium-magnesium enolates derived from 2,4,6-trimethylacetophenone

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Abstract

The reactivity of the stoichiometric variant monosodium-monomagnesium trialkyl NaMgBu3 and disodium-monomagnesium tetraalkyl Na2MgBu4 complexes toward the sterically demanding ketone 2,4,6-trimethylacetophenone has been investigated and led to the synthesis of a series of mixed sodium-magnesium enolate complexes. Thus, 2 and 3 molar equiv of the ketone with NaMgBu3 produce heteroanionic [Na2Mg2(-Bu)2{-OC(=CH2)Mes}4(TMEDA)2] (6) and homoanionic [Na2Mg2{-OC(=CH2)Mes}6(TMEDA)2] (4), respectively, while 4 equiv of the ketone with Na2MgBu4 affords homoanionic [Na2Mg{-OC(=CH2)Mes}4(TMEDA)2] (5). X-ray crystallographic studies reveal that 4 and 6 adopt similar tetranuclear Na···Mg···Mg···Na chain arrangements, held together by enolato O bridges in the former and a mixture of enolato O and alkyl C bridges in the latter, whereas 5 adopts a smaller trinuclear Na···Mg···Na chain arrangement with all enolato O bridges. The metal coordination in all these structures is distorted tetrahedral, while the sodium cations at the ends of the mixed-metal chains carry terminal TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 are also reported for 4-6. For comparative purposes, the synthesis and X-ray crystal structure of the homometallic sodium enolate [Na2{OC(=CH2)Mes}2(TMEDA)2] (7), a simple enolate O-bridged dimer, is also reported.
Original languageEnglish
Pages (from-to)1778-1785
Number of pages7
JournalOrganometallics
Volume25
Issue number7
DOIs
Publication statusPublished - 4 Mar 2006

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ketones
Magnesium
magnesium
Metals
Sodium
sodium
Ketones
synthesis
metals
x rays
reactivity
X rays
dimers
cations
nuclear magnetic resonance
ligands
crystal structure
Dimers
Cations
Crystal structure

Keywords

  • sodium-magnesium
  • trimethylacetophenone

Cite this

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title = "Synthesis and characterization of new mixed-metal sodium-magnesium enolates derived from 2,4,6-trimethylacetophenone",
abstract = "The reactivity of the stoichiometric variant monosodium-monomagnesium trialkyl NaMgBu3 and disodium-monomagnesium tetraalkyl Na2MgBu4 complexes toward the sterically demanding ketone 2,4,6-trimethylacetophenone has been investigated and led to the synthesis of a series of mixed sodium-magnesium enolate complexes. Thus, 2 and 3 molar equiv of the ketone with NaMgBu3 produce heteroanionic [Na2Mg2(-Bu)2{-OC(=CH2)Mes}4(TMEDA)2] (6) and homoanionic [Na2Mg2{-OC(=CH2)Mes}6(TMEDA)2] (4), respectively, while 4 equiv of the ketone with Na2MgBu4 affords homoanionic [Na2Mg{-OC(=CH2)Mes}4(TMEDA)2] (5). X-ray crystallographic studies reveal that 4 and 6 adopt similar tetranuclear Na···Mg···Mg···Na chain arrangements, held together by enolato O bridges in the former and a mixture of enolato O and alkyl C bridges in the latter, whereas 5 adopts a smaller trinuclear Na···Mg···Na chain arrangement with all enolato O bridges. The metal coordination in all these structures is distorted tetrahedral, while the sodium cations at the ends of the mixed-metal chains carry terminal TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 are also reported for 4-6. For comparative purposes, the synthesis and X-ray crystal structure of the homometallic sodium enolate [Na2{OC(=CH2)Mes}2(TMEDA)2] (7), a simple enolate O-bridged dimer, is also reported.",
keywords = "sodium-magnesium, trimethylacetophenone",
author = "E. Hevia and K.W. Henderson and A.R. Kennedy and R.E. Mulvey",
year = "2006",
month = "3",
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doi = "10.1021/om051076c",
language = "English",
volume = "25",
pages = "1778--1785",
journal = "Organometallics",
issn = "0276-7333",
publisher = "American Chemical Society",
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}

Synthesis and characterization of new mixed-metal sodium-magnesium enolates derived from 2,4,6-trimethylacetophenone. / Hevia, E.; Henderson, K.W.; Kennedy, A.R.; Mulvey, R.E.

In: Organometallics, Vol. 25, No. 7, 04.03.2006, p. 1778-1785.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis and characterization of new mixed-metal sodium-magnesium enolates derived from 2,4,6-trimethylacetophenone

AU - Hevia, E.

AU - Henderson, K.W.

AU - Kennedy, A.R.

AU - Mulvey, R.E.

PY - 2006/3/4

Y1 - 2006/3/4

N2 - The reactivity of the stoichiometric variant monosodium-monomagnesium trialkyl NaMgBu3 and disodium-monomagnesium tetraalkyl Na2MgBu4 complexes toward the sterically demanding ketone 2,4,6-trimethylacetophenone has been investigated and led to the synthesis of a series of mixed sodium-magnesium enolate complexes. Thus, 2 and 3 molar equiv of the ketone with NaMgBu3 produce heteroanionic [Na2Mg2(-Bu)2{-OC(=CH2)Mes}4(TMEDA)2] (6) and homoanionic [Na2Mg2{-OC(=CH2)Mes}6(TMEDA)2] (4), respectively, while 4 equiv of the ketone with Na2MgBu4 affords homoanionic [Na2Mg{-OC(=CH2)Mes}4(TMEDA)2] (5). X-ray crystallographic studies reveal that 4 and 6 adopt similar tetranuclear Na···Mg···Mg···Na chain arrangements, held together by enolato O bridges in the former and a mixture of enolato O and alkyl C bridges in the latter, whereas 5 adopts a smaller trinuclear Na···Mg···Na chain arrangement with all enolato O bridges. The metal coordination in all these structures is distorted tetrahedral, while the sodium cations at the ends of the mixed-metal chains carry terminal TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 are also reported for 4-6. For comparative purposes, the synthesis and X-ray crystal structure of the homometallic sodium enolate [Na2{OC(=CH2)Mes}2(TMEDA)2] (7), a simple enolate O-bridged dimer, is also reported.

AB - The reactivity of the stoichiometric variant monosodium-monomagnesium trialkyl NaMgBu3 and disodium-monomagnesium tetraalkyl Na2MgBu4 complexes toward the sterically demanding ketone 2,4,6-trimethylacetophenone has been investigated and led to the synthesis of a series of mixed sodium-magnesium enolate complexes. Thus, 2 and 3 molar equiv of the ketone with NaMgBu3 produce heteroanionic [Na2Mg2(-Bu)2{-OC(=CH2)Mes}4(TMEDA)2] (6) and homoanionic [Na2Mg2{-OC(=CH2)Mes}6(TMEDA)2] (4), respectively, while 4 equiv of the ketone with Na2MgBu4 affords homoanionic [Na2Mg{-OC(=CH2)Mes}4(TMEDA)2] (5). X-ray crystallographic studies reveal that 4 and 6 adopt similar tetranuclear Na···Mg···Mg···Na chain arrangements, held together by enolato O bridges in the former and a mixture of enolato O and alkyl C bridges in the latter, whereas 5 adopts a smaller trinuclear Na···Mg···Na chain arrangement with all enolato O bridges. The metal coordination in all these structures is distorted tetrahedral, while the sodium cations at the ends of the mixed-metal chains carry terminal TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 are also reported for 4-6. For comparative purposes, the synthesis and X-ray crystal structure of the homometallic sodium enolate [Na2{OC(=CH2)Mes}2(TMEDA)2] (7), a simple enolate O-bridged dimer, is also reported.

KW - sodium-magnesium

KW - trimethylacetophenone

UR - http://dx.doi.org/10.1021/om051076c

U2 - 10.1021/om051076c

DO - 10.1021/om051076c

M3 - Article

VL - 25

SP - 1778

EP - 1785

JO - Organometallics

JF - Organometallics

SN - 0276-7333

IS - 7

ER -