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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.
Original language | English |
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Pages (from-to) | 5332-5341 |
Number of pages | 10 |
Journal | Dalton Transactions |
Volume | 40 |
Issue number | 19 |
DOIs | |
Publication status | Published - 31 Mar 2011 |
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
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Dive into the research topics of 'Synthesis and structural chemistry of alkali metal tris(HMDS) magnesiates containing chiral diamine donor ligands'. Together they form a unique fingerprint.Projects
- 1 Finished
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ENANTIOSELECTIVE APPLICATIONS OF DESIGNER SYNERGIC REAGENTS (First Grant)
O'Hara, C. (Principal Investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/08 → 31/03/12
Project: Research