Solvent induced disproportionation of alkyl(amido)magnesium species containing a (2-pyridyl)amido unit: Synthetic, theoretical and NMR spectroscopic studies of bis(amido)magnesium compounds

K.W. Henderson, Robert Mulvey, A.E. Dorigo

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Abstract

Reaction of R(2-pyr)NH (where R = Me, Ph or 2-pyr) with 'Bu(2)Mg' in an ether-free environment yields the corresponding alkyl(amido)magnesium derivative [{R(2-pyr)NMgBu}(n)]. When polar solvent is added to these species only bis(amido)magnesium compounds separate from solution and not the expected solvated alkyl(amido) derivatives. Isolation of one such alkyl(amido) compound prior to reaction with donor solvent proves that the mixed anion species do indeed exist, However, when polar molecules are introduced a disproportionation reaction ensues, yielding the homoleptic compounds [{R(2)Mg .(S)(x)}(n)] and [{(R(2)N)(2)Mg .(S)(x)}(n)], where S is THF, TMEDA or PMDETA. Theoretical calculations likewise show that the disproportionation reaction of model compounds closely related to our systems is strongly exothermic. A H-1/C-13 NMR spectroscopic study was used to assign the nature of the bis(amido) species in solution. From these analyses it was possible to propose that the solvated bis(amido) derivatives assume a common structural motif, that of a monomer (n = 1) with a pseudo-octahedral magnesium center.

LanguageEnglish
Pages139-146
Number of pages8
JournalJournal of Organometallic Chemistry
Volume518
Issue number1-2
DOIs
Publication statusPublished - 12 Jul 1996

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Magnesium Compounds
Magnesium compounds
magnesium compounds
Magnesium
magnesium
Nuclear magnetic resonance
Derivatives
nuclear magnetic resonance
Ether
Anions
alkyl compounds
Ethers
Negative ions
Monomers
ethers
isolation
Molecules
monomers
anions
molecules

Keywords

  • magnesium
  • amido
  • ab initio MO calculations
  • disproportionation
  • ray crystal structures
  • aryl compounds
  • metal alkyl
  • colligative measurements
  • solid state
  • lithium
  • tetrahydrofuran
  • amides
  • complexes
  • reagent

Cite this

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title = "Solvent induced disproportionation of alkyl(amido)magnesium species containing a (2-pyridyl)amido unit: Synthetic, theoretical and NMR spectroscopic studies of bis(amido)magnesium compounds",
abstract = "Reaction of R(2-pyr)NH (where R = Me, Ph or 2-pyr) with 'Bu(2)Mg' in an ether-free environment yields the corresponding alkyl(amido)magnesium derivative [{R(2-pyr)NMgBu}(n)]. When polar solvent is added to these species only bis(amido)magnesium compounds separate from solution and not the expected solvated alkyl(amido) derivatives. Isolation of one such alkyl(amido) compound prior to reaction with donor solvent proves that the mixed anion species do indeed exist, However, when polar molecules are introduced a disproportionation reaction ensues, yielding the homoleptic compounds [{R(2)Mg .(S)(x)}(n)] and [{(R(2)N)(2)Mg .(S)(x)}(n)], where S is THF, TMEDA or PMDETA. Theoretical calculations likewise show that the disproportionation reaction of model compounds closely related to our systems is strongly exothermic. A H-1/C-13 NMR spectroscopic study was used to assign the nature of the bis(amido) species in solution. From these analyses it was possible to propose that the solvated bis(amido) derivatives assume a common structural motif, that of a monomer (n = 1) with a pseudo-octahedral magnesium center.",
keywords = "magnesium, amido, ab initio MO calculations, disproportionation, ray crystal structures, aryl compounds, metal alkyl, colligative measurements, solid state, lithium, tetrahydrofuran, amides, complexes, reagent",
author = "K.W. Henderson and Robert Mulvey and A.E. Dorigo",
year = "1996",
month = "7",
day = "12",
doi = "10.1016/0022-328X(96)06202-X",
language = "English",
volume = "518",
pages = "139--146",
journal = "Journal of Organometallic Chemistry",
issn = "0022-328X",
number = "1-2",

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TY - JOUR

T1 - Solvent induced disproportionation of alkyl(amido)magnesium species containing a (2-pyridyl)amido unit

T2 - Journal of Organometallic Chemistry

AU - Henderson, K.W.

AU - Mulvey, Robert

AU - Dorigo, A.E.

PY - 1996/7/12

Y1 - 1996/7/12

N2 - Reaction of R(2-pyr)NH (where R = Me, Ph or 2-pyr) with 'Bu(2)Mg' in an ether-free environment yields the corresponding alkyl(amido)magnesium derivative [{R(2-pyr)NMgBu}(n)]. When polar solvent is added to these species only bis(amido)magnesium compounds separate from solution and not the expected solvated alkyl(amido) derivatives. Isolation of one such alkyl(amido) compound prior to reaction with donor solvent proves that the mixed anion species do indeed exist, However, when polar molecules are introduced a disproportionation reaction ensues, yielding the homoleptic compounds [{R(2)Mg .(S)(x)}(n)] and [{(R(2)N)(2)Mg .(S)(x)}(n)], where S is THF, TMEDA or PMDETA. Theoretical calculations likewise show that the disproportionation reaction of model compounds closely related to our systems is strongly exothermic. A H-1/C-13 NMR spectroscopic study was used to assign the nature of the bis(amido) species in solution. From these analyses it was possible to propose that the solvated bis(amido) derivatives assume a common structural motif, that of a monomer (n = 1) with a pseudo-octahedral magnesium center.

AB - Reaction of R(2-pyr)NH (where R = Me, Ph or 2-pyr) with 'Bu(2)Mg' in an ether-free environment yields the corresponding alkyl(amido)magnesium derivative [{R(2-pyr)NMgBu}(n)]. When polar solvent is added to these species only bis(amido)magnesium compounds separate from solution and not the expected solvated alkyl(amido) derivatives. Isolation of one such alkyl(amido) compound prior to reaction with donor solvent proves that the mixed anion species do indeed exist, However, when polar molecules are introduced a disproportionation reaction ensues, yielding the homoleptic compounds [{R(2)Mg .(S)(x)}(n)] and [{(R(2)N)(2)Mg .(S)(x)}(n)], where S is THF, TMEDA or PMDETA. Theoretical calculations likewise show that the disproportionation reaction of model compounds closely related to our systems is strongly exothermic. A H-1/C-13 NMR spectroscopic study was used to assign the nature of the bis(amido) species in solution. From these analyses it was possible to propose that the solvated bis(amido) derivatives assume a common structural motif, that of a monomer (n = 1) with a pseudo-octahedral magnesium center.

KW - magnesium

KW - amido

KW - ab initio MO calculations

KW - disproportionation

KW - ray crystal structures

KW - aryl compounds

KW - metal alkyl

KW - colligative measurements

KW - solid state

KW - lithium

KW - tetrahydrofuran

KW - amides

KW - complexes

KW - reagent

U2 - 10.1016/0022-328X(96)06202-X

DO - 10.1016/0022-328X(96)06202-X

M3 - Article

VL - 518

SP - 139

EP - 146

JO - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

IS - 1-2

ER -