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From cyclic amines and acetonitrile to amidine zinc(ii) complexes
A seemingly simple combination of [Zn(quin)(2)(H(2)O)] (quin(−) = quinaldinate) and a selected secondary cyclic amine, piperidine (pipe), pyrrolidine (pyro) or morpholine (morph), afforded in acetonitrile a number of products: anionic homoleptic quinaldinate, neutral heteroleptic quinaldinate/amine...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053709/ https://www.ncbi.nlm.nih.gov/pubmed/35517198 http://dx.doi.org/10.1039/d0ra03192e |
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author | Podjed, Nina Modec, Barbara Alcaide, María M. López-Serrano, Joaquín |
author_facet | Podjed, Nina Modec, Barbara Alcaide, María M. López-Serrano, Joaquín |
author_sort | Podjed, Nina |
collection | PubMed |
description | A seemingly simple combination of [Zn(quin)(2)(H(2)O)] (quin(−) = quinaldinate) and a selected secondary cyclic amine, piperidine (pipe), pyrrolidine (pyro) or morpholine (morph), afforded in acetonitrile a number of products: anionic homoleptic quinaldinate, neutral heteroleptic quinaldinate/amine and quinaldinate/amidine complexes. The piperidine and pyrrolidine systems underwent reaction with acetonitrile to give amidines. The in situ formed piperidinoacetamidine (pipeam) or pyrrolidinoacetamidine (pyroam) coordinated to zinc(ii). Reactions with piperidine led to trans-[Zn(quin)(2)(pipe)(2)]·2CH(3)CN (1), [Zn(quin)(2)(pipe)]·cis-[Zn(quin)(2)(pipe)(2)] (2), pipeH[Zn(quin)(3)]·CH(3)CN (3), [Zn(quin)(2)(pipeam)]·CH(3)CN (4a), [Zn(quin)(2)(pipeam)]·2CHCl(3) (4b), pipeamH[Zn(quin)(3)] (5) and pipeamH[Zn(quin)(2)(CH(3)COO)]·acetamide (6) (pipeH(+) and pipeamH(+) denote protonated amine or amidine). By analogy, [Zn(quin)(2)(pyro)(2)] (7), pyroH[Zn(quin)(3)]·CH(3)CN (8), pyroH[Zn(quin)(2)Cl] (9), [Zn(quin)(2)(pyroam)]·CH(3)CN·0.5pyroam·0.5H(2)O (10a), [Zn(quin)(2)(pyroam)]·2CHCl(3) (10b), [Zn(quin)(2)(pyroam)]·CH(2)Cl(2) (10c) and pyroamH[Zn(quin)(3)] (11) were obtained in the pyrrolidine reactions. The morpholine system allowed isolation of only two novel products, trans-[Zn(quin)(2)(morph)(2)] (12) and morphH[Zn(quin)(3)]·CH(3)CN (13). Importantly, no amidine could be isolated. Instead, in autoclaves at 105 °C morpholine degraded to ammonia, as confirmed by mass spectrometry of the gas phase. pyroamH[Zn(quin)(3)] exists in two polymorphs which differ in the binding modes of quinaldinate ligands. In 11triclinic, the metal ion of [Zn(quin)(3)](−) features a five-coordinate environment, whereas that in 11monoclinic is surrounded by six donors. Stabilities of the [Zn(quin)(3)](−) isomers were assessed with DFT calculations. The one with a six-coordinate zinc(ii) ion was found to be more stable than its five-coordinate counterpart. Favorable intermolecular interactions in the solid state stabilize both and reduce the energy difference between them. The calculations show the conversion of the five-coordinate [Zn(quin)(3)](−) into its coordinatively saturated isomer to be an almost barrierless process. |
format | Online Article Text |
id | pubmed-9053709 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | The Royal Society of Chemistry |
record_format | MEDLINE/PubMed |
spelling | pubmed-90537092022-05-04 From cyclic amines and acetonitrile to amidine zinc(ii) complexes Podjed, Nina Modec, Barbara Alcaide, María M. López-Serrano, Joaquín RSC Adv Chemistry A seemingly simple combination of [Zn(quin)(2)(H(2)O)] (quin(−) = quinaldinate) and a selected secondary cyclic amine, piperidine (pipe), pyrrolidine (pyro) or morpholine (morph), afforded in acetonitrile a number of products: anionic homoleptic quinaldinate, neutral heteroleptic quinaldinate/amine and quinaldinate/amidine complexes. The piperidine and pyrrolidine systems underwent reaction with acetonitrile to give amidines. The in situ formed piperidinoacetamidine (pipeam) or pyrrolidinoacetamidine (pyroam) coordinated to zinc(ii). Reactions with piperidine led to trans-[Zn(quin)(2)(pipe)(2)]·2CH(3)CN (1), [Zn(quin)(2)(pipe)]·cis-[Zn(quin)(2)(pipe)(2)] (2), pipeH[Zn(quin)(3)]·CH(3)CN (3), [Zn(quin)(2)(pipeam)]·CH(3)CN (4a), [Zn(quin)(2)(pipeam)]·2CHCl(3) (4b), pipeamH[Zn(quin)(3)] (5) and pipeamH[Zn(quin)(2)(CH(3)COO)]·acetamide (6) (pipeH(+) and pipeamH(+) denote protonated amine or amidine). By analogy, [Zn(quin)(2)(pyro)(2)] (7), pyroH[Zn(quin)(3)]·CH(3)CN (8), pyroH[Zn(quin)(2)Cl] (9), [Zn(quin)(2)(pyroam)]·CH(3)CN·0.5pyroam·0.5H(2)O (10a), [Zn(quin)(2)(pyroam)]·2CHCl(3) (10b), [Zn(quin)(2)(pyroam)]·CH(2)Cl(2) (10c) and pyroamH[Zn(quin)(3)] (11) were obtained in the pyrrolidine reactions. The morpholine system allowed isolation of only two novel products, trans-[Zn(quin)(2)(morph)(2)] (12) and morphH[Zn(quin)(3)]·CH(3)CN (13). Importantly, no amidine could be isolated. Instead, in autoclaves at 105 °C morpholine degraded to ammonia, as confirmed by mass spectrometry of the gas phase. pyroamH[Zn(quin)(3)] exists in two polymorphs which differ in the binding modes of quinaldinate ligands. In 11triclinic, the metal ion of [Zn(quin)(3)](−) features a five-coordinate environment, whereas that in 11monoclinic is surrounded by six donors. Stabilities of the [Zn(quin)(3)](−) isomers were assessed with DFT calculations. The one with a six-coordinate zinc(ii) ion was found to be more stable than its five-coordinate counterpart. Favorable intermolecular interactions in the solid state stabilize both and reduce the energy difference between them. The calculations show the conversion of the five-coordinate [Zn(quin)(3)](−) into its coordinatively saturated isomer to be an almost barrierless process. The Royal Society of Chemistry 2020-05-13 /pmc/articles/PMC9053709/ /pubmed/35517198 http://dx.doi.org/10.1039/d0ra03192e Text en This journal is © The Royal Society of Chemistry https://creativecommons.org/licenses/by-nc/3.0/ |
spellingShingle | Chemistry Podjed, Nina Modec, Barbara Alcaide, María M. López-Serrano, Joaquín From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title | From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title_full | From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title_fullStr | From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title_full_unstemmed | From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title_short | From cyclic amines and acetonitrile to amidine zinc(ii) complexes |
title_sort | from cyclic amines and acetonitrile to amidine zinc(ii) complexes |
topic | Chemistry |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9053709/ https://www.ncbi.nlm.nih.gov/pubmed/35517198 http://dx.doi.org/10.1039/d0ra03192e |
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