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Targeted structural modification of spin crossover complexes: pyridine vs pyrazine

Targeted structural modification of spin crossover complexes: pyridine vs pyrazine
Targeted structural modification of spin crossover complexes: pyridine vs pyrazine

2-(Aminomethyl)pyrazine has been prepared in five steps from 2-pyrazine carboxylic acid. From this key amine, two new bis-terdentate triazole-based ligands which feature pendant pyrazine groups, PZMAT and PZMPT (4-amino- and 4-pyrrolyl-3,5-bis{[(2-pyrazylmethyl)amino]methyl}-4H-1,2,4-triazole, respectively), and two dinuclear complexes of them, [FeII 2(PZMAT)2](BF4)4∙MeOH∙2H2O (1∙MeOH∙2H2O) and [FeII 2(PZMPT)2](BF4)4∙3H2O (2∙3H2O), have been prepared. A structure determination at 100 K on 2∙3.5MeCN confirmed that the ligands adopt the expected binding mode, providing all twelve donors to the two iron(II) centres and two N1,N2-triazole bridges between them. Both undergo gradual incomplete spin transitions: at room temperature 1∙MeOH∙2H2O and 2∙3H2O are approximately two-thirds to three-quarters [HS-HS], dropping to mostly ‘[HS-LS]’ at 50 K. The structure determination and Mössbauer spectroscopy of 2 qualitatively support this. These findings are consistent with the pendant pyrazines providing a somewhat higher field strength than the pendant pyridines do in the analogous PMRT complexes.

2-(aminomethyl)pyrazine; heterocycle, dinuclear, iron(II), pyrazine, Spin crossover, triazole
1061-0278
296-304
Feltham, Humphrey L.C.
343099f1-b760-408c-8ade-ef93e1a9a746
Cowan, Matthew G.
9637c7ba-b172-4655-a2f0-03b92d0d8101
Kitchen, Jonathan A.
3999f5cb-d53e-4c51-b750-627bd2a1b9b6
Jameson, Guy N.L.
6c485bbe-c1b1-4ea5-8cb5-973731cd24b9
Brooker, Sally
2ee9681a-3ff7-41be-88c5-681f66b953ef
Feltham, Humphrey L.C.
343099f1-b760-408c-8ade-ef93e1a9a746
Cowan, Matthew G.
9637c7ba-b172-4655-a2f0-03b92d0d8101
Kitchen, Jonathan A.
3999f5cb-d53e-4c51-b750-627bd2a1b9b6
Jameson, Guy N.L.
6c485bbe-c1b1-4ea5-8cb5-973731cd24b9
Brooker, Sally
2ee9681a-3ff7-41be-88c5-681f66b953ef

Feltham, Humphrey L.C., Cowan, Matthew G., Kitchen, Jonathan A., Jameson, Guy N.L. and Brooker, Sally (2018) Targeted structural modification of spin crossover complexes: pyridine vs pyrazine. Supramolecular Chemistry, 30 (4), 296-304. (doi:10.1080/10610278.2017.1358449).

Record type: Article

Abstract

2-(Aminomethyl)pyrazine has been prepared in five steps from 2-pyrazine carboxylic acid. From this key amine, two new bis-terdentate triazole-based ligands which feature pendant pyrazine groups, PZMAT and PZMPT (4-amino- and 4-pyrrolyl-3,5-bis{[(2-pyrazylmethyl)amino]methyl}-4H-1,2,4-triazole, respectively), and two dinuclear complexes of them, [FeII 2(PZMAT)2](BF4)4∙MeOH∙2H2O (1∙MeOH∙2H2O) and [FeII 2(PZMPT)2](BF4)4∙3H2O (2∙3H2O), have been prepared. A structure determination at 100 K on 2∙3.5MeCN confirmed that the ligands adopt the expected binding mode, providing all twelve donors to the two iron(II) centres and two N1,N2-triazole bridges between them. Both undergo gradual incomplete spin transitions: at room temperature 1∙MeOH∙2H2O and 2∙3H2O are approximately two-thirds to three-quarters [HS-HS], dropping to mostly ‘[HS-LS]’ at 50 K. The structure determination and Mössbauer spectroscopy of 2 qualitatively support this. These findings are consistent with the pendant pyrazines providing a somewhat higher field strength than the pendant pyridines do in the analogous PMRT complexes.

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More information

Accepted/In Press date: 18 July 2017
e-pub ahead of print date: 18 August 2017
Published date: 3 April 2018
Keywords: 2-(aminomethyl)pyrazine; heterocycle, dinuclear, iron(II), pyrazine, Spin crossover, triazole

Identifiers

Local EPrints ID: 418091
URI: http://eprints.soton.ac.uk/id/eprint/418091
ISSN: 1061-0278
PURE UUID: 07003d9f-36a4-4119-8188-cf3b3c07b69c
ORCID for Jonathan A. Kitchen: ORCID iD orcid.org/0000-0002-7139-5666

Catalogue record

Date deposited: 22 Feb 2018 17:30
Last modified: 17 Mar 2024 11:59

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Contributors

Author: Humphrey L.C. Feltham
Author: Matthew G. Cowan
Author: Jonathan A. Kitchen ORCID iD
Author: Guy N.L. Jameson
Author: Sally Brooker

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