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Pyrrole-Based Ti(III) and Ti(IV) PNP Pincer Complexes: Insertion of Ketones into the Ti(IV)-Phosphorus Bond
[Image: see text] The synthesis, characterization, and reactivity of pyrrole-based Ti(III) and Ti(IV) PNP pincer complexes are described. [P(NH)P-iPr] (1) reacts with [TiCl(4)(THF)(2)] at room temperature in the presence of NEt(3) to afford the Ti(IV) complex [Ti(PNP(iPr))(Cl)(3)]. This complex reac...
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2023
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10598877/ https://www.ncbi.nlm.nih.gov/pubmed/37886626 http://dx.doi.org/10.1021/acs.organomet.3c00327 |
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author | Tomsu, Gerald Stöger, Berthold Kirchner, Karl |
author_facet | Tomsu, Gerald Stöger, Berthold Kirchner, Karl |
author_sort | Tomsu, Gerald |
collection | PubMed |
description | [Image: see text] The synthesis, characterization, and reactivity of pyrrole-based Ti(III) and Ti(IV) PNP pincer complexes are described. [P(NH)P-iPr] (1) reacts with [TiCl(4)(THF)(2)] at room temperature in the presence of NEt(3) to afford the Ti(IV) complex [Ti(PNP(iPr))(Cl)(3)]. This complex reacts with acetone and cyclopentanone to give complexes [Ti(PNO(acet)-iPr)(Cl)(3)] and [Ti(PNO(cyclo)-iPr)(Cl)(3)], respectively. Insertion of the ketone into the Ti(IV)-P bond took place, forming a new tridendate PNO-ligand. Treatment of [TiCl(3)(THF)(3)] with the lithium salt of [P(NH)P-iPr] afforded, upon workup, complex [Ti(PNP-iPr)(Cl)(2)(THF)], a paramagnetic complex with an μ(eff) value of 1.8(1) μ(B) which corresponds to one unpaired electron and a formal oxidation state of +III. This compound does not react with ketones. A mechanistic proposal based on DFT calculations is presented. Ketone insertion proceeds via an associative reaction initiated by ketone coordination at the metal center, followed by the opening of the five-membered chelate ring, and finally an intramolecular nucleophilic attack of the noncoordinated phosphine arm at the carbonyl atom of the ketone. All complexes were characterized by X-ray crystallography. |
format | Online Article Text |
id | pubmed-10598877 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2023 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-105988772023-10-26 Pyrrole-Based Ti(III) and Ti(IV) PNP Pincer Complexes: Insertion of Ketones into the Ti(IV)-Phosphorus Bond Tomsu, Gerald Stöger, Berthold Kirchner, Karl Organometallics [Image: see text] The synthesis, characterization, and reactivity of pyrrole-based Ti(III) and Ti(IV) PNP pincer complexes are described. [P(NH)P-iPr] (1) reacts with [TiCl(4)(THF)(2)] at room temperature in the presence of NEt(3) to afford the Ti(IV) complex [Ti(PNP(iPr))(Cl)(3)]. This complex reacts with acetone and cyclopentanone to give complexes [Ti(PNO(acet)-iPr)(Cl)(3)] and [Ti(PNO(cyclo)-iPr)(Cl)(3)], respectively. Insertion of the ketone into the Ti(IV)-P bond took place, forming a new tridendate PNO-ligand. Treatment of [TiCl(3)(THF)(3)] with the lithium salt of [P(NH)P-iPr] afforded, upon workup, complex [Ti(PNP-iPr)(Cl)(2)(THF)], a paramagnetic complex with an μ(eff) value of 1.8(1) μ(B) which corresponds to one unpaired electron and a formal oxidation state of +III. This compound does not react with ketones. A mechanistic proposal based on DFT calculations is presented. Ketone insertion proceeds via an associative reaction initiated by ketone coordination at the metal center, followed by the opening of the five-membered chelate ring, and finally an intramolecular nucleophilic attack of the noncoordinated phosphine arm at the carbonyl atom of the ketone. All complexes were characterized by X-ray crystallography. American Chemical Society 2023-10-05 /pmc/articles/PMC10598877/ /pubmed/37886626 http://dx.doi.org/10.1021/acs.organomet.3c00327 Text en © 2023 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Tomsu, Gerald Stöger, Berthold Kirchner, Karl Pyrrole-Based Ti(III) and Ti(IV) PNP Pincer Complexes: Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title | Pyrrole-Based
Ti(III) and Ti(IV) PNP Pincer Complexes:
Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title_full | Pyrrole-Based
Ti(III) and Ti(IV) PNP Pincer Complexes:
Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title_fullStr | Pyrrole-Based
Ti(III) and Ti(IV) PNP Pincer Complexes:
Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title_full_unstemmed | Pyrrole-Based
Ti(III) and Ti(IV) PNP Pincer Complexes:
Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title_short | Pyrrole-Based
Ti(III) and Ti(IV) PNP Pincer Complexes:
Insertion of Ketones into the Ti(IV)-Phosphorus Bond |
title_sort | pyrrole-based
ti(iii) and ti(iv) pnp pincer complexes:
insertion of ketones into the ti(iv)-phosphorus bond |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10598877/ https://www.ncbi.nlm.nih.gov/pubmed/37886626 http://dx.doi.org/10.1021/acs.organomet.3c00327 |
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