Abstract
| Original language | English |
|---|---|
| Pages (from-to) | 1477-1484 |
| Number of pages | 7 |
| Journal | Journal of the Chemical Society, Dalton Transactions |
| Volume | 2001 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 2001 |
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Keywords
- crown ether complexes
- crystal structures
- macrocyclic amide
- metal amides
- hexamathyldislazide
- benzonitrile
- reactivity
- prydine
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Structural chemistry of monodentate donor-solvated mixed lithium-magnesium secondary amide complexes. / Forbes, G.C.; Kennedy, A.R.; Mulvey, R.E.; Rodger, P.J.A.; Rowlings, R.B.
In: Journal of the Chemical Society, Dalton Transactions, Vol. 2001, No. 9, 2001, p. 1477-1484.Research output: Contribution to journal › Article
TY - JOUR
T1 - Structural chemistry of monodentate donor-solvated mixed lithium-magnesium secondary amide complexes
AU - Forbes, G.C.
AU - Kennedy, A.R.
AU - Mulvey, R.E.
AU - Rodger, P.J.A.
AU - Rowlings, R.B.
PY - 2001
Y1 - 2001
N2 - The monodentate donor-solvated intermetallic lithium-magnesium amide complexes [Mg(HMDS)(3)Li . (THF)] 1 [HMDS=N(SiMe3)(2)], [Mg(HMDS)(3)Li . (Pyr)] 2 and [Mg{N(Cy)(2)}(3)Li . (THF)] 3 [N(Cy)(2)=dicyclohexylamide] have been prepared and characterised by NMR spectroscopy and X-ray crystallography. Synthesis was achieved by the reaction of equimolar amounts of n-BuLi and n,sec-Bu2Mg with three equivalents of the appropriate amine in hexane/donor solution. The molecular structures of 1, 2 and 3 are essentially isostructural containing a central, planar LiNMgN four-membered ring: two amide units bridge to the metal centres whilst the third binds exclusively to magnesium in the terminal position to complete a three-coordinate distorted trigonal planar geometry. The lithium achieves a similar geometry with solvation from a single monodentate donor molecule. Three co-crystalline by-products were also isolated from solution and are included for completeness: [Mg(HMDS)(2)(Bu)Li . Pyr] 4, [(LiHMDS . Pyr)(2)] 5 and [Mg(HMDS)(2). (Pyr)(2)] 6. Complex 4 exhibits a similar structure to 1, 2 and 3 with an alkyl group (consisting of disordered n- and sec-butyl groups) replacing the terminal amido functionality. Complex 4 is produced by a similar method to 2 via incomplete amination in the presence of two equivalents of hexamethyldisilazane (HMDS(H)). In contrast, 5 and 6 are simple homometallic amides formed when an excess of pyridine is introduced into the reaction system. To conclude the study a series of reactions were undertaken in which the stoichiometry of both amine and donor was altered systematically. The results from this study imply that intermetallic aggregation is hindered by the presence of excess donor solvent.
AB - The monodentate donor-solvated intermetallic lithium-magnesium amide complexes [Mg(HMDS)(3)Li . (THF)] 1 [HMDS=N(SiMe3)(2)], [Mg(HMDS)(3)Li . (Pyr)] 2 and [Mg{N(Cy)(2)}(3)Li . (THF)] 3 [N(Cy)(2)=dicyclohexylamide] have been prepared and characterised by NMR spectroscopy and X-ray crystallography. Synthesis was achieved by the reaction of equimolar amounts of n-BuLi and n,sec-Bu2Mg with three equivalents of the appropriate amine in hexane/donor solution. The molecular structures of 1, 2 and 3 are essentially isostructural containing a central, planar LiNMgN four-membered ring: two amide units bridge to the metal centres whilst the third binds exclusively to magnesium in the terminal position to complete a three-coordinate distorted trigonal planar geometry. The lithium achieves a similar geometry with solvation from a single monodentate donor molecule. Three co-crystalline by-products were also isolated from solution and are included for completeness: [Mg(HMDS)(2)(Bu)Li . Pyr] 4, [(LiHMDS . Pyr)(2)] 5 and [Mg(HMDS)(2). (Pyr)(2)] 6. Complex 4 exhibits a similar structure to 1, 2 and 3 with an alkyl group (consisting of disordered n- and sec-butyl groups) replacing the terminal amido functionality. Complex 4 is produced by a similar method to 2 via incomplete amination in the presence of two equivalents of hexamethyldisilazane (HMDS(H)). In contrast, 5 and 6 are simple homometallic amides formed when an excess of pyridine is introduced into the reaction system. To conclude the study a series of reactions were undertaken in which the stoichiometry of both amine and donor was altered systematically. The results from this study imply that intermetallic aggregation is hindered by the presence of excess donor solvent.
KW - crown ether complexes
KW - crystal structures
KW - macrocyclic amide
KW - metal amides
KW - hexamathyldislazide
KW - benzonitrile
KW - reactivity
KW - prydine
UR - http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleForFree.cfm?doi=b105009p&JournalCode=CC
UR - http://dx.doi.org/10.1039/b100052g
U2 - 10.1039/b100052g
DO - 10.1039/b100052g
M3 - Article
VL - 2001
SP - 1477
EP - 1484
JO - Journal of the Chemical Society, Dalton Transactions
JF - Journal of the Chemical Society, Dalton Transactions
SN - 0300-9246
IS - 9
ER -