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Molecules, Vol. 23, Pages 1138: Structural Characterization of Lithium and Sodium Bulky Bis(silyl)amide Complexes

Molecules, Vol. 23, Pages 1138: Structural Characterization of Lithium and Sodium Bulky Bis(silyl)amide Complexes

Molecules doi: 10.3390/molecules23051138

Authors: Hannah M. Nicholas Conrad A. P. Goodwin Jon G. C. Kragskow Selena J. Lockyer David P. Mills

Alkali metal amides are vital reagents in synthetic chemistry and the bis(silyl)amide {N(SiMe3)2} (N′′) is one of the most widely-utilized examples. Given that N′′ has provided landmark complexes, we have investigated synthetic routes to lithium and sodium bis(silyl)amides with increased steric bulk to analyse the effects of R-group substitution on structural features. To perform this study, the bulky bis(silyl)amines {HN(SitBuMe2)(SiMe3)}, {HN(SiiPr3)(SiMe3)}, {HN(SitBuMe2)2}, {HN(SiiPr3)(SitBuMe2)} and {HN(SiiPr3)2} (1) were prepared by literature procedures as colourless oils; on one occasion crystals of 1 were obtained. These were treated separately with nBuLi to afford the respective lithium bis(silyl)amides [Li{μ-N(SitBuMe2)(SiMe3)}]2 (2), [Li{μ-N(SiiPr3)(SiMe3)}]2 (3), [Li{N(SitBuMe2)2}{μ-N(SitBuMe2)2}Li(THF)] (4), [Li{N(SiiPr3)(SitBuMe2)}(DME)] (6) and [Li{N(SiiPr3)2}(THF)] (7) following workup and recrystallization. On one occasion during the synthesis of 4 several crystals of the ‘ate’ complex [Li2{μ-N(SitBuMe2)2}(μ-nBu)]2 (5) formed and a trace amount of [Li{N(SiiPr3)2}(THF)2] (8) was identified during the recrystallization of 7. The reaction of {HN(SitBuMe2)2} with NaH in the presence of 2 mol % of NaOtBu gave crystals of [Na{μ-N(SitBuMe2)2}(THF)]2 (9-THF), whilst [Na{N(SiiPr3)2}(C7H8)] (10) was prepared by deprotonation of 1 with nBuNa. The solid-state structures of 1–10 were determined by single crystal X-ray crystallography, whilst 2–4, 7, 9 and 10 were additionally characterized by NMR and FTIR spectroscopy and elemental microanalysis.

Authors:   Nicholas, Hannah M.; Goodwin, Conrad A. P.; Kragskow, Jon G. C.; Lockyer, Selena J.; Mills, David P.
Journal:   Molecules
Volume:   23
edition:   5
Year:   2018
Pages:   1138
DOI:   10.3390/molecules23051138
Publication date:   10-May-2018
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