Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands

Pablo Garcia-Alvarez, Alan R. Kennedy, Charles T. O'Hara, Kieran Reilly, Gemma M. Robertson

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Six alkali metal tris(HMDS) magnesiate complexes (HMDS, 1,1,1,3,3,3,-hexamethyldisilazide) containing chiral diamine ligands have been prepared and characterised in both the solid- and solution-state. Four of the complexes have a solvent-separated ion pair composition of the form [{M∙(chiral diamine)2}+{Mg(HMDS)3}−] [M = Li for 1 and 3, Na for 2 and 4; chiral diamine = (−)-sparteine for 1 and 2, (R,R)-TMCDA for 3 and 4, (where (R,R)-TMCDA is N,N,N′,N'-(1R,2R)-tetramethylcyclohexane-1,2-diamine)] and two have a contacted ion pair composition of the form [{K∙chiral diamine}+{Mg(HMDS)3}−]n [chiral diamine = (−)-sparteine for 5 and (R,R)-TMCDA for 6]. In the solid-state, complexes 1–4 are essentially isostructural, with the lithium or sodium cation sequestered by the respective chiral diamine and the previously reported anion consisting of three HMDS ligands coordinated to a magnesium centre. As such, complexes 1–4 are the first structurally characterised complexes in which the alkali metal is sequestered by two molecules of either of the chiral diamines (–)-sparteine (1 and 2) or (R,R)-TMCDA (3 and 4). In addition, complex 4 is a rare (R,R)-TMCDA adduct of sodium. In the solid state, complexes 5 and 6 exist as polymeric arrays of dimeric [{K∙chiral diamine}+{Mg(HMDS)3}−]2 subunits, with 5 adopting a two-dimensional net arrangement and 6 a linear arrangement. As such, complexes 5 and 6 appear to be the only structurally characterised complexes in which the chiral diamines (–)-sparteine (5) or (R,R)-TMCDA (6) have been incorporated within a polymeric framework. In addition, prior to this work, no (−)-sparteine or (R,R)-TMCDA adducts of potassium had been reported.
LanguageEnglish
Pages5332-5341
Number of pages10
JournalDalton Transactions
Volume40
Issue number19
DOIs
Publication statusPublished - 31 Mar 2011

Fingerprint

Alkali Metals
Diamines
Sparteine
Ligands
Sodium
Ions
Chemical analysis
Lithium
Magnesium
Anions
Cations
Potassium

Keywords

  • sparteine-mediated deprotonation
  • inverse crown-ether
  • enantioselective lithiation-substitution
  • carbon bond formations
  • cation-pi interactions
  • asymmetric-synthesis
  • crystal-structures
  • conjugate additions
  • amide chemistry
  • n-boc-pyrrolidine

Cite this

@article{82164b084980408e87e14a4b1eee68b9,
title = "Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands",
abstract = "Six alkali metal tris(HMDS) magnesiate complexes (HMDS, 1,1,1,3,3,3,-hexamethyldisilazide) containing chiral diamine ligands have been prepared and characterised in both the solid- and solution-state. Four of the complexes have a solvent-separated ion pair composition of the form [{M∙(chiral diamine)2}+{Mg(HMDS)3}−] [M = Li for 1 and 3, Na for 2 and 4; chiral diamine = (−)-sparteine for 1 and 2, (R,R)-TMCDA for 3 and 4, (where (R,R)-TMCDA is N,N,N′,N'-(1R,2R)-tetramethylcyclohexane-1,2-diamine)] and two have a contacted ion pair composition of the form [{K∙chiral diamine}+{Mg(HMDS)3}−]n [chiral diamine = (−)-sparteine for 5 and (R,R)-TMCDA for 6]. In the solid-state, complexes 1–4 are essentially isostructural, with the lithium or sodium cation sequestered by the respective chiral diamine and the previously reported anion consisting of three HMDS ligands coordinated to a magnesium centre. As such, complexes 1–4 are the first structurally characterised complexes in which the alkali metal is sequestered by two molecules of either of the chiral diamines (–)-sparteine (1 and 2) or (R,R)-TMCDA (3 and 4). In addition, complex 4 is a rare (R,R)-TMCDA adduct of sodium. In the solid state, complexes 5 and 6 exist as polymeric arrays of dimeric [{K∙chiral diamine}+{Mg(HMDS)3}−]2 subunits, with 5 adopting a two-dimensional net arrangement and 6 a linear arrangement. As such, complexes 5 and 6 appear to be the only structurally characterised complexes in which the chiral diamines (–)-sparteine (5) or (R,R)-TMCDA (6) have been incorporated within a polymeric framework. In addition, prior to this work, no (−)-sparteine or (R,R)-TMCDA adducts of potassium had been reported.",
keywords = "sparteine-mediated deprotonation , inverse crown-ether, enantioselective lithiation-substitution , carbon bond formations , cation-pi interactions, asymmetric-synthesis , crystal-structures, conjugate additions, amide chemistry, n-boc-pyrrolidine",
author = "Pablo Garcia-Alvarez and Kennedy, {Alan R.} and O'Hara, {Charles T.} and Kieran Reilly and Robertson, {Gemma M.}",
year = "2011",
month = "3",
day = "31",
doi = "10.1039/c1dt10058k",
language = "English",
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pages = "5332--5341",
journal = "Dalton Transactions",
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Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands. / Garcia-Alvarez, Pablo; Kennedy, Alan R.; O'Hara, Charles T.; Reilly, Kieran; Robertson, Gemma M.

In: Dalton Transactions, Vol. 40, No. 19, 31.03.2011, p. 5332-5341.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands

AU - Garcia-Alvarez, Pablo

AU - Kennedy, Alan R.

AU - O'Hara, Charles T.

AU - Reilly, Kieran

AU - Robertson, Gemma M.

PY - 2011/3/31

Y1 - 2011/3/31

N2 - Six alkali metal tris(HMDS) magnesiate complexes (HMDS, 1,1,1,3,3,3,-hexamethyldisilazide) containing chiral diamine ligands have been prepared and characterised in both the solid- and solution-state. Four of the complexes have a solvent-separated ion pair composition of the form [{M∙(chiral diamine)2}+{Mg(HMDS)3}−] [M = Li for 1 and 3, Na for 2 and 4; chiral diamine = (−)-sparteine for 1 and 2, (R,R)-TMCDA for 3 and 4, (where (R,R)-TMCDA is N,N,N′,N'-(1R,2R)-tetramethylcyclohexane-1,2-diamine)] and two have a contacted ion pair composition of the form [{K∙chiral diamine}+{Mg(HMDS)3}−]n [chiral diamine = (−)-sparteine for 5 and (R,R)-TMCDA for 6]. In the solid-state, complexes 1–4 are essentially isostructural, with the lithium or sodium cation sequestered by the respective chiral diamine and the previously reported anion consisting of three HMDS ligands coordinated to a magnesium centre. As such, complexes 1–4 are the first structurally characterised complexes in which the alkali metal is sequestered by two molecules of either of the chiral diamines (–)-sparteine (1 and 2) or (R,R)-TMCDA (3 and 4). In addition, complex 4 is a rare (R,R)-TMCDA adduct of sodium. In the solid state, complexes 5 and 6 exist as polymeric arrays of dimeric [{K∙chiral diamine}+{Mg(HMDS)3}−]2 subunits, with 5 adopting a two-dimensional net arrangement and 6 a linear arrangement. As such, complexes 5 and 6 appear to be the only structurally characterised complexes in which the chiral diamines (–)-sparteine (5) or (R,R)-TMCDA (6) have been incorporated within a polymeric framework. In addition, prior to this work, no (−)-sparteine or (R,R)-TMCDA adducts of potassium had been reported.

AB - Six alkali metal tris(HMDS) magnesiate complexes (HMDS, 1,1,1,3,3,3,-hexamethyldisilazide) containing chiral diamine ligands have been prepared and characterised in both the solid- and solution-state. Four of the complexes have a solvent-separated ion pair composition of the form [{M∙(chiral diamine)2}+{Mg(HMDS)3}−] [M = Li for 1 and 3, Na for 2 and 4; chiral diamine = (−)-sparteine for 1 and 2, (R,R)-TMCDA for 3 and 4, (where (R,R)-TMCDA is N,N,N′,N'-(1R,2R)-tetramethylcyclohexane-1,2-diamine)] and two have a contacted ion pair composition of the form [{K∙chiral diamine}+{Mg(HMDS)3}−]n [chiral diamine = (−)-sparteine for 5 and (R,R)-TMCDA for 6]. In the solid-state, complexes 1–4 are essentially isostructural, with the lithium or sodium cation sequestered by the respective chiral diamine and the previously reported anion consisting of three HMDS ligands coordinated to a magnesium centre. As such, complexes 1–4 are the first structurally characterised complexes in which the alkali metal is sequestered by two molecules of either of the chiral diamines (–)-sparteine (1 and 2) or (R,R)-TMCDA (3 and 4). In addition, complex 4 is a rare (R,R)-TMCDA adduct of sodium. In the solid state, complexes 5 and 6 exist as polymeric arrays of dimeric [{K∙chiral diamine}+{Mg(HMDS)3}−]2 subunits, with 5 adopting a two-dimensional net arrangement and 6 a linear arrangement. As such, complexes 5 and 6 appear to be the only structurally characterised complexes in which the chiral diamines (–)-sparteine (5) or (R,R)-TMCDA (6) have been incorporated within a polymeric framework. In addition, prior to this work, no (−)-sparteine or (R,R)-TMCDA adducts of potassium had been reported.

KW - sparteine-mediated deprotonation

KW - inverse crown-ether

KW - enantioselective lithiation-substitution

KW - carbon bond formations

KW - cation-pi interactions

KW - asymmetric-synthesis

KW - crystal-structures

KW - conjugate additions

KW - amide chemistry

KW - n-boc-pyrrolidine

U2 - 10.1039/c1dt10058k

DO - 10.1039/c1dt10058k

M3 - Article

VL - 40

SP - 5332

EP - 5341

JO - Dalton Transactions

T2 - Dalton Transactions

JF - Dalton Transactions

SN - 1477-9226

IS - 19

ER -