Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones

The first amidinate-stabilized aryloxosilylene [LSi(OAr)] (II, L = PhC(NtBu)2, Ar = 2,6-tBu2-4-MeC6H2) was synthesized by the reaction of the amidinate-stabilized chlorosilylene I with lithium 2,6-di-tert-butyl-4-methylphenyloxide in E120. After that, the amidinate-stabilized aryloxosilylene-bor...

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Main Author: Tian, Jin
Other Authors: Cheuk-Wai So
Format: Theses and Dissertations
Language:English
Published: 2016
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Online Access:http://hdl.handle.net/10356/68883
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Institution: Nanyang Technological University
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spelling sg-ntu-dr.10356-688832023-02-28T23:33:54Z Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones Tian, Jin Cheuk-Wai So School of Physical and Mathematical Sciences DRNTU::Science::Chemistry The first amidinate-stabilized aryloxosilylene [LSi(OAr)] (II, L = PhC(NtBu)2, Ar = 2,6-tBu2-4-MeC6H2) was synthesized by the reaction of the amidinate-stabilized chlorosilylene I with lithium 2,6-di-tert-butyl-4-methylphenyloxide in E120. After that, the amidinate-stabilized aryloxosilylene-borane adduct [L(ArO)Si~BH3] (III) and the amidinate-stabilized aryloxosilanechalcogenones [L(ArO)Si=E] [E = S (IV) and Se (V)] were synthesized by treatment of II with BH3, elemental sulfur and elemental selenium, respectively. The structures of the amidinate-stabilized aryloxosilylene, aryloxosilylene-borane adduct and aryloxosilanechalcogenones were determined by X-ray crystallography, and NMR spectroscopy. The 29Si NMR results showed that the amidinate-stabilized aryloxo silanechalcogenones [L(ArO)Si=E] [E = S (IV) and Se (V)] are upfield shifted compared with those of three-coordinate silanechalcogenones with Si=E double bond. However, the coupling constant of the silicon atom with the selenium atom in V is larger than that in the silaneselenide containing bridging Si-Se bonds. In the solid state, the four-membered Si-N-C-N rings in compounds II, III, IV and V are planner, and the phenyl rings are orthogonal to these planes. In addition, the bond lengths of C-N bonds are intermediate between single and double bond lengths, which indicate that the N-C-N skeletons are partially conjugated and there are electron delocalizations. From the X-ray crystallographic data, the bond lengths of the Si=E bonds [E = S (IV) and Se (V)] are intermediate between double and single bond due to the resonance structures between the Si=E double bond structure and the strongly delocalized Si+-E- single bond structure. ​Master of Science 2016-07-01T07:54:40Z 2016-07-01T07:54:40Z 2016 Thesis http://hdl.handle.net/10356/68883 en 28 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Science::Chemistry
spellingShingle DRNTU::Science::Chemistry
Tian, Jin
Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
description The first amidinate-stabilized aryloxosilylene [LSi(OAr)] (II, L = PhC(NtBu)2, Ar = 2,6-tBu2-4-MeC6H2) was synthesized by the reaction of the amidinate-stabilized chlorosilylene I with lithium 2,6-di-tert-butyl-4-methylphenyloxide in E120. After that, the amidinate-stabilized aryloxosilylene-borane adduct [L(ArO)Si~BH3] (III) and the amidinate-stabilized aryloxosilanechalcogenones [L(ArO)Si=E] [E = S (IV) and Se (V)] were synthesized by treatment of II with BH3, elemental sulfur and elemental selenium, respectively. The structures of the amidinate-stabilized aryloxosilylene, aryloxosilylene-borane adduct and aryloxosilanechalcogenones were determined by X-ray crystallography, and NMR spectroscopy. The 29Si NMR results showed that the amidinate-stabilized aryloxo silanechalcogenones [L(ArO)Si=E] [E = S (IV) and Se (V)] are upfield shifted compared with those of three-coordinate silanechalcogenones with Si=E double bond. However, the coupling constant of the silicon atom with the selenium atom in V is larger than that in the silaneselenide containing bridging Si-Se bonds. In the solid state, the four-membered Si-N-C-N rings in compounds II, III, IV and V are planner, and the phenyl rings are orthogonal to these planes. In addition, the bond lengths of C-N bonds are intermediate between single and double bond lengths, which indicate that the N-C-N skeletons are partially conjugated and there are electron delocalizations. From the X-ray crystallographic data, the bond lengths of the Si=E bonds [E = S (IV) and Se (V)] are intermediate between double and single bond due to the resonance structures between the Si=E double bond structure and the strongly delocalized Si+-E- single bond structure.
author2 Cheuk-Wai So
author_facet Cheuk-Wai So
Tian, Jin
format Theses and Dissertations
author Tian, Jin
author_sort Tian, Jin
title Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
title_short Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
title_full Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
title_fullStr Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
title_full_unstemmed Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
title_sort heavier ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones
publishDate 2016
url http://hdl.handle.net/10356/68883
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