Synthesis and characterisation of new bimetallic alkali metal-magnesium mixed diisopropylamide-acetylides: structural variations in bimetallic lithium- and sodium-heteroleptic magnesiates

J. Garcia-Alvarez, D.V. Graham, E. Hevia, A.R. Kennedy, R.E. Mulvey

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Abstract

The reactivity of the Brønsted basic mixed-metal tris-amide compounds of empirical formula [MMg(NiPr2)3] [where M = Li ( 1), Na ( 2)] towards phenylacetylene (HCCPh) has been investigated and has led to the synthesis of a series of mixed-metal acetylido-amido-magnesiates. Thus, 1 and 2 molar equivalents of the alkyne with [MMg(NiPr2)3] produce heteroanionic bis(amido)-mono(acetylido) [LiMg(NiPr2)2(CCPh)]2 ( 3) and mono(amido)-bis(acetylido) [(TMEDA)·Na(CCPh)2Mg(NiPr2)]2 ( 4) (TMEDA = N,N,N,N-tetramethylethylenediamine) respectively. X-Ray crystallographic studies reveal that the new compounds adopt a different structural motif. Complex 3 can be defined as an inverse crown structure, having a cationic eight-atom [(NaNMgN)2]2+ ring which hosts in its core two acetylido ligands. On the other hand, 4 adopts a tetranuclear NaMgMgNa near-linear chain arrangement, held together by acetylido and amido bridges. The metal coordination geometries in both structures are distorted tetrahedral, and the sodium cations at the end of the mixed-metal chain carry terminal chelating TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 solutions are also reported for 3 and 4, and are consistent with the solid-state structures being retained in solution.
LanguageEnglish
Pages1481-1486
Number of pages5
JournalDalton Transactions
Issue number11
DOIs
Publication statusPublished - 2008

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Alkali Metals
Lithium
Magnesium
Metals
Sodium
Ligands
Alkynes
Chelation
Amides
Cations
Nuclear magnetic resonance
X rays
Atoms
Geometry
phenyllithium

Keywords

  • directed ortho-metalation
  • inverse crown chemistry
  • cross-coupling symbiosis
  • aryl compounds
  • crystal-structures
  • molecular-structure
  • alkyl
  • complexes
  • deprotonation
  • phenylethynyl

Cite this

@article{39ee910ad5f944c1a75ec2b64df09676,
title = "Synthesis and characterisation of new bimetallic alkali metal-magnesium mixed diisopropylamide-acetylides: structural variations in bimetallic lithium- and sodium-heteroleptic magnesiates",
abstract = "The reactivity of the Br{\o}nsted basic mixed-metal tris-amide compounds of empirical formula [MMg(NiPr2)3] [where M = Li ( 1), Na ( 2)] towards phenylacetylene (HCCPh) has been investigated and has led to the synthesis of a series of mixed-metal acetylido-amido-magnesiates. Thus, 1 and 2 molar equivalents of the alkyne with [MMg(NiPr2)3] produce heteroanionic bis(amido)-mono(acetylido) [LiMg(NiPr2)2(CCPh)]2 ( 3) and mono(amido)-bis(acetylido) [(TMEDA)·Na(CCPh)2Mg(NiPr2)]2 ( 4) (TMEDA = N,N,N,N-tetramethylethylenediamine) respectively. X-Ray crystallographic studies reveal that the new compounds adopt a different structural motif. Complex 3 can be defined as an inverse crown structure, having a cationic eight-atom [(NaNMgN)2]2+ ring which hosts in its core two acetylido ligands. On the other hand, 4 adopts a tetranuclear NaMgMgNa near-linear chain arrangement, held together by acetylido and amido bridges. The metal coordination geometries in both structures are distorted tetrahedral, and the sodium cations at the end of the mixed-metal chain carry terminal chelating TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 solutions are also reported for 3 and 4, and are consistent with the solid-state structures being retained in solution.",
keywords = "directed ortho-metalation, inverse crown chemistry, cross-coupling symbiosis, aryl compounds, crystal-structures, molecular-structure, alkyl, complexes, deprotonation, phenylethynyl",
author = "J. Garcia-Alvarez and D.V. Graham and E. Hevia and A.R. Kennedy and R.E. Mulvey",
year = "2008",
doi = "10.1039/b716215d",
language = "English",
pages = "1481--1486",
journal = "Dalton Transactions",
issn = "1477-9226",
number = "11",

}

TY - JOUR

T1 - Synthesis and characterisation of new bimetallic alkali metal-magnesium mixed diisopropylamide-acetylides: structural variations in bimetallic lithium- and sodium-heteroleptic magnesiates

AU - Garcia-Alvarez, J.

AU - Graham, D.V.

AU - Hevia, E.

AU - Kennedy, A.R.

AU - Mulvey, R.E.

PY - 2008

Y1 - 2008

N2 - The reactivity of the Brønsted basic mixed-metal tris-amide compounds of empirical formula [MMg(NiPr2)3] [where M = Li ( 1), Na ( 2)] towards phenylacetylene (HCCPh) has been investigated and has led to the synthesis of a series of mixed-metal acetylido-amido-magnesiates. Thus, 1 and 2 molar equivalents of the alkyne with [MMg(NiPr2)3] produce heteroanionic bis(amido)-mono(acetylido) [LiMg(NiPr2)2(CCPh)]2 ( 3) and mono(amido)-bis(acetylido) [(TMEDA)·Na(CCPh)2Mg(NiPr2)]2 ( 4) (TMEDA = N,N,N,N-tetramethylethylenediamine) respectively. X-Ray crystallographic studies reveal that the new compounds adopt a different structural motif. Complex 3 can be defined as an inverse crown structure, having a cationic eight-atom [(NaNMgN)2]2+ ring which hosts in its core two acetylido ligands. On the other hand, 4 adopts a tetranuclear NaMgMgNa near-linear chain arrangement, held together by acetylido and amido bridges. The metal coordination geometries in both structures are distorted tetrahedral, and the sodium cations at the end of the mixed-metal chain carry terminal chelating TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 solutions are also reported for 3 and 4, and are consistent with the solid-state structures being retained in solution.

AB - The reactivity of the Brønsted basic mixed-metal tris-amide compounds of empirical formula [MMg(NiPr2)3] [where M = Li ( 1), Na ( 2)] towards phenylacetylene (HCCPh) has been investigated and has led to the synthesis of a series of mixed-metal acetylido-amido-magnesiates. Thus, 1 and 2 molar equivalents of the alkyne with [MMg(NiPr2)3] produce heteroanionic bis(amido)-mono(acetylido) [LiMg(NiPr2)2(CCPh)]2 ( 3) and mono(amido)-bis(acetylido) [(TMEDA)·Na(CCPh)2Mg(NiPr2)]2 ( 4) (TMEDA = N,N,N,N-tetramethylethylenediamine) respectively. X-Ray crystallographic studies reveal that the new compounds adopt a different structural motif. Complex 3 can be defined as an inverse crown structure, having a cationic eight-atom [(NaNMgN)2]2+ ring which hosts in its core two acetylido ligands. On the other hand, 4 adopts a tetranuclear NaMgMgNa near-linear chain arrangement, held together by acetylido and amido bridges. The metal coordination geometries in both structures are distorted tetrahedral, and the sodium cations at the end of the mixed-metal chain carry terminal chelating TMEDA ligands. 1H and 13C NMR spectral data recorded in C6D6 solutions are also reported for 3 and 4, and are consistent with the solid-state structures being retained in solution.

KW - directed ortho-metalation

KW - inverse crown chemistry

KW - cross-coupling symbiosis

KW - aryl compounds

KW - crystal-structures

KW - molecular-structure

KW - alkyl

KW - complexes

KW - deprotonation

KW - phenylethynyl

UR - http://dx.doi.org/10.1039/b716215d

U2 - 10.1039/b716215d

DO - 10.1039/b716215d

M3 - Article

SP - 1481

EP - 1486

JO - Dalton Transactions

T2 - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 11

ER -