Magnesium aryloxides: synthesis, structure, solution behavior and magnesiate ion formation

K.W. Henderson, G.W. Honeyman, A.R. Kennedy, R.E. Mulvey, J.A. Parkinson, D.C. Sherrington

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

The heteroleptic magnesium complexes [{Ar'OMgBu}(2)] 1 and [{Ar'OMgN(i-Pr)(2)}(2)] 2, where OAr' = 2,6-di-tertbutylphenoxy, have been prepared and found to be dimeric in the solid state, with tri-coordinate metal centers. Complex 1 utilizes the aryloxide anions as bridging groups whereas the amido anions connect the metals in 2. Addition of THF or TMEDA to hydrocarbon solutions containing 2 results in disproportionation and the exclusive precipitation of the homoleptic, solvated, complexes [Mg(OAr')(2).2THF] 3 or [Mg(OAr')(2).TMEDA] 4. Both 3 and 4 are monomeric in the solid state with tetra-coordinate magnesium centers. Solution NMR spectroscopic studies of 1 and 2 reveal that disproportionation to the homoleptic complexes is promoted in THF-d(8) but that the main component still appears to be the heteroleptic species. Dissolution of the unsolvated dimeric complex [Mg(OAr')(2)] 5 in THF-d(8) results in partial formation of the magnesiate complex [Ar'OMg](+)[(Ar'O)(3)Mg](-)10, along with the monomer 3. In contrast, no magnesiate is formed on dissolution of 3 in THF-d(8), indicating that magnesiate formation most likely proceeds via unsymmetrical cleavage of the dimer. Ab initio calculations (HF/6-31G*) have been used to investigate the possible structures of the magnesiate species.
LanguageEnglish
Pages1365-1372
Number of pages7
JournalDalton Transactions
Volume2003
Issue number7
DOIs
Publication statusPublished - 2003

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Magnesium
Anions
Dissolution
Metals
Ions
Hydrocarbons
Dimers
Monomers
Nuclear magnetic resonance
phenyllithium

Keywords

  • MOLECULAR-ORBITAL METHODS
  • ALKALINE-EARTH METALS
  • ENANTIOSELECTIVE DEPROTONATION
  • DIALKYLMAGNESIUM COMPOUNDS
  • CRYSTAL-STRUCTURES
  • AMIDE BASE
  • LITHIUM ALKOXIDES
  • NITRILE OXIDE
  • BASIS SETS
  • SOLVENT

Cite this

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title = "Magnesium aryloxides: synthesis, structure, solution behavior and magnesiate ion formation",
abstract = "The heteroleptic magnesium complexes [{Ar'OMgBu}(2)] 1 and [{Ar'OMgN(i-Pr)(2)}(2)] 2, where OAr' = 2,6-di-tertbutylphenoxy, have been prepared and found to be dimeric in the solid state, with tri-coordinate metal centers. Complex 1 utilizes the aryloxide anions as bridging groups whereas the amido anions connect the metals in 2. Addition of THF or TMEDA to hydrocarbon solutions containing 2 results in disproportionation and the exclusive precipitation of the homoleptic, solvated, complexes [Mg(OAr')(2).2THF] 3 or [Mg(OAr')(2).TMEDA] 4. Both 3 and 4 are monomeric in the solid state with tetra-coordinate magnesium centers. Solution NMR spectroscopic studies of 1 and 2 reveal that disproportionation to the homoleptic complexes is promoted in THF-d(8) but that the main component still appears to be the heteroleptic species. Dissolution of the unsolvated dimeric complex [Mg(OAr')(2)] 5 in THF-d(8) results in partial formation of the magnesiate complex [Ar'OMg](+)[(Ar'O)(3)Mg](-)10, along with the monomer 3. In contrast, no magnesiate is formed on dissolution of 3 in THF-d(8), indicating that magnesiate formation most likely proceeds via unsymmetrical cleavage of the dimer. Ab initio calculations (HF/6-31G*) have been used to investigate the possible structures of the magnesiate species.",
keywords = "MOLECULAR-ORBITAL METHODS, ALKALINE-EARTH METALS, ENANTIOSELECTIVE DEPROTONATION, DIALKYLMAGNESIUM COMPOUNDS, CRYSTAL-STRUCTURES, AMIDE BASE, LITHIUM ALKOXIDES, NITRILE OXIDE, BASIS SETS, SOLVENT",
author = "K.W. Henderson and G.W. Honeyman and A.R. Kennedy and R.E. Mulvey and J.A. Parkinson and D.C. Sherrington",
year = "2003",
doi = "10.1039/b212608g",
language = "English",
volume = "2003",
pages = "1365--1372",
journal = "Dalton Transactions",
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Magnesium aryloxides: synthesis, structure, solution behavior and magnesiate ion formation. / Henderson, K.W.; Honeyman, G.W.; Kennedy, A.R.; Mulvey, R.E.; Parkinson, J.A.; Sherrington, D.C.

In: Dalton Transactions, Vol. 2003, No. 7, 2003, p. 1365-1372.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Magnesium aryloxides: synthesis, structure, solution behavior and magnesiate ion formation

AU - Henderson, K.W.

AU - Honeyman, G.W.

AU - Kennedy, A.R.

AU - Mulvey, R.E.

AU - Parkinson, J.A.

AU - Sherrington, D.C.

PY - 2003

Y1 - 2003

N2 - The heteroleptic magnesium complexes [{Ar'OMgBu}(2)] 1 and [{Ar'OMgN(i-Pr)(2)}(2)] 2, where OAr' = 2,6-di-tertbutylphenoxy, have been prepared and found to be dimeric in the solid state, with tri-coordinate metal centers. Complex 1 utilizes the aryloxide anions as bridging groups whereas the amido anions connect the metals in 2. Addition of THF or TMEDA to hydrocarbon solutions containing 2 results in disproportionation and the exclusive precipitation of the homoleptic, solvated, complexes [Mg(OAr')(2).2THF] 3 or [Mg(OAr')(2).TMEDA] 4. Both 3 and 4 are monomeric in the solid state with tetra-coordinate magnesium centers. Solution NMR spectroscopic studies of 1 and 2 reveal that disproportionation to the homoleptic complexes is promoted in THF-d(8) but that the main component still appears to be the heteroleptic species. Dissolution of the unsolvated dimeric complex [Mg(OAr')(2)] 5 in THF-d(8) results in partial formation of the magnesiate complex [Ar'OMg](+)[(Ar'O)(3)Mg](-)10, along with the monomer 3. In contrast, no magnesiate is formed on dissolution of 3 in THF-d(8), indicating that magnesiate formation most likely proceeds via unsymmetrical cleavage of the dimer. Ab initio calculations (HF/6-31G*) have been used to investigate the possible structures of the magnesiate species.

AB - The heteroleptic magnesium complexes [{Ar'OMgBu}(2)] 1 and [{Ar'OMgN(i-Pr)(2)}(2)] 2, where OAr' = 2,6-di-tertbutylphenoxy, have been prepared and found to be dimeric in the solid state, with tri-coordinate metal centers. Complex 1 utilizes the aryloxide anions as bridging groups whereas the amido anions connect the metals in 2. Addition of THF or TMEDA to hydrocarbon solutions containing 2 results in disproportionation and the exclusive precipitation of the homoleptic, solvated, complexes [Mg(OAr')(2).2THF] 3 or [Mg(OAr')(2).TMEDA] 4. Both 3 and 4 are monomeric in the solid state with tetra-coordinate magnesium centers. Solution NMR spectroscopic studies of 1 and 2 reveal that disproportionation to the homoleptic complexes is promoted in THF-d(8) but that the main component still appears to be the heteroleptic species. Dissolution of the unsolvated dimeric complex [Mg(OAr')(2)] 5 in THF-d(8) results in partial formation of the magnesiate complex [Ar'OMg](+)[(Ar'O)(3)Mg](-)10, along with the monomer 3. In contrast, no magnesiate is formed on dissolution of 3 in THF-d(8), indicating that magnesiate formation most likely proceeds via unsymmetrical cleavage of the dimer. Ab initio calculations (HF/6-31G*) have been used to investigate the possible structures of the magnesiate species.

KW - MOLECULAR-ORBITAL METHODS

KW - ALKALINE-EARTH METALS

KW - ENANTIOSELECTIVE DEPROTONATION

KW - DIALKYLMAGNESIUM COMPOUNDS

KW - CRYSTAL-STRUCTURES

KW - AMIDE BASE

KW - LITHIUM ALKOXIDES

KW - NITRILE OXIDE

KW - BASIS SETS

KW - SOLVENT

UR - http://dx.doi.org/10.1039/b212608g

U2 - 10.1039/b212608g

DO - 10.1039/b212608g

M3 - Article

VL - 2003

SP - 1365

EP - 1372

JO - Dalton Transactions

T2 - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 7

ER -