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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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 |
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DRNTU::Science::Chemistry Tian, Jin Heavier Ester analogues : synthesis of amidinate-stabilized aryloxo silanechalcogenones |
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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 |
_version_ |
1759853442849832960 |