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Molecules. 2018 May 10;23(5). pii: E1138. doi: 10.3390/molecules23051138.

Structural Characterization of Lithium and Sodium Bulky Bis(silyl)amide Complexes.

Author information

1
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. hannah.nicholas@manchester.ac.uk.
2
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. conrad.goodwin@manchester.ac.uk.
3
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. jon.kragskow@student.manchester.ac.uk.
4
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. selena.lockyer@postgrad.manchester.ac.uk.
5
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK. david.mills@manchester.ac.uk.

Abstract

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 110 were determined by single crystal X-ray crystallography, whilst 24, 7, 9 and 10 were additionally characterized by NMR and FTIR spectroscopy and elemental microanalysis.

KEYWORDS:

bis(silyl)amide; ligand; lithium; sodium

PMID:
29748490
DOI:
10.3390/molecules23051138
[Indexed for MEDLINE]
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