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Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride

Reaction of the thorium metallacycle, [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] (R = SiMe(3)) with 1 equiv. of NaNH(2) in THF, in the presence of 18-crown-6, results in formation of the bridged thorium nitride complex, [Na(18-crown-6)(Et(2)O)][(R(2)N)(3)Th(μ-N)(Th(NR(2))(3)] ([Na][1]), which can be isolate...

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Autores principales: Staun, Selena L., Sergentu, Dumitru-Claudiu, Wu, Guang, Autschbach, Jochen, Hayton, Trevor W.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Royal Society of Chemistry 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615217/
https://www.ncbi.nlm.nih.gov/pubmed/31367305
http://dx.doi.org/10.1039/c9sc01960j
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author Staun, Selena L.
Sergentu, Dumitru-Claudiu
Wu, Guang
Autschbach, Jochen
Hayton, Trevor W.
author_facet Staun, Selena L.
Sergentu, Dumitru-Claudiu
Wu, Guang
Autschbach, Jochen
Hayton, Trevor W.
author_sort Staun, Selena L.
collection PubMed
description Reaction of the thorium metallacycle, [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] (R = SiMe(3)) with 1 equiv. of NaNH(2) in THF, in the presence of 18-crown-6, results in formation of the bridged thorium nitride complex, [Na(18-crown-6)(Et(2)O)][(R(2)N)(3)Th(μ-N)(Th(NR(2))(3)] ([Na][1]), which can be isolated in 66% yield after work-up. Complex [Na][1] is the first isolable molecular thorium nitride complex. Mechanistic studies suggest that the first step of the reaction is deprotonation of [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] by NaNH(2), which results in formation of the thorium bis(metallacycle) complex, [Na(THF)(x)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))], and NH(3). NH(3) then reacts with unreacted [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)], forming [Th(NR(2))(3)(NH(2))] (2), which protonates [Na(THF)(x)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))] to give [Na][1]. Consistent with hypothesis, addition of excess NH(3) to a THF solution of [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] results in formation of [Th(NR(2))(3)(NH(2))] (2), which can be isolated in 51% yield after work-up. Furthermore, reaction of [K(DME)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))] with 2, in THF-d(8), results in clean formation of [K][1], according to (1)H NMR spectroscopy. The electronic structures of [1](–) and 2 were investigated by (15)N NMR spectroscopy and DFT calculations. This analysis reveals that the Th–N(nitride) bond in [1](–) features more covalency and a greater degree of bond multiplicity than the Th–NH(2) bond in 2. Similarly, our analysis indicates a greater degree of covalency in [1](–)vs. comparable thorium imido and oxo complexes.
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spelling pubmed-66152172019-07-31 Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride Staun, Selena L. Sergentu, Dumitru-Claudiu Wu, Guang Autschbach, Jochen Hayton, Trevor W. Chem Sci Chemistry Reaction of the thorium metallacycle, [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] (R = SiMe(3)) with 1 equiv. of NaNH(2) in THF, in the presence of 18-crown-6, results in formation of the bridged thorium nitride complex, [Na(18-crown-6)(Et(2)O)][(R(2)N)(3)Th(μ-N)(Th(NR(2))(3)] ([Na][1]), which can be isolated in 66% yield after work-up. Complex [Na][1] is the first isolable molecular thorium nitride complex. Mechanistic studies suggest that the first step of the reaction is deprotonation of [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] by NaNH(2), which results in formation of the thorium bis(metallacycle) complex, [Na(THF)(x)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))], and NH(3). NH(3) then reacts with unreacted [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)], forming [Th(NR(2))(3)(NH(2))] (2), which protonates [Na(THF)(x)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))] to give [Na][1]. Consistent with hypothesis, addition of excess NH(3) to a THF solution of [Th{N(R)(SiMe(2))CH(2)}(NR(2))(2)] results in formation of [Th(NR(2))(3)(NH(2))] (2), which can be isolated in 51% yield after work-up. Furthermore, reaction of [K(DME)][Th{N(R)(SiMe(2)CH(2))}(2)(NR(2))] with 2, in THF-d(8), results in clean formation of [K][1], according to (1)H NMR spectroscopy. The electronic structures of [1](–) and 2 were investigated by (15)N NMR spectroscopy and DFT calculations. This analysis reveals that the Th–N(nitride) bond in [1](–) features more covalency and a greater degree of bond multiplicity than the Th–NH(2) bond in 2. Similarly, our analysis indicates a greater degree of covalency in [1](–)vs. comparable thorium imido and oxo complexes. Royal Society of Chemistry 2019-06-04 /pmc/articles/PMC6615217/ /pubmed/31367305 http://dx.doi.org/10.1039/c9sc01960j Text en This journal is © The Royal Society of Chemistry 2019 https://creativecommons.org/licenses/by-nc/3.0/This article is freely available. This article is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported Licence (CC BY-NC 3.0)
spellingShingle Chemistry
Staun, Selena L.
Sergentu, Dumitru-Claudiu
Wu, Guang
Autschbach, Jochen
Hayton, Trevor W.
Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title_full Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title_fullStr Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title_full_unstemmed Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title_short Use of (15)N NMR spectroscopy to probe covalency in a thorium nitride
title_sort use of (15)n nmr spectroscopy to probe covalency in a thorium nitride
topic Chemistry
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615217/
https://www.ncbi.nlm.nih.gov/pubmed/31367305
http://dx.doi.org/10.1039/c9sc01960j
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