Exceptionally high temperature spin crossover in amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine iron(ii) complex revealed by variable temperature Raman spectroscopy and single crystal X-ray diffraction

Attwood, M., Akutsu, H., Martin, L. ORCID: 0000-0002-5330-5700, Blundell, T.J. ORCID: 0000-0002-7296-1471, Le Maguere, P. and Turner, S.S., 2021. Exceptionally high temperature spin crossover in amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine iron(ii) complex revealed by variable temperature Raman spectroscopy and single crystal X-ray diffraction. Dalton Transactions. ISSN 1477-9226

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Abstract

The synthesis of a novel amide-functionalised 2,6-bis(pyrazol-1-yl)pyridine-4-carboxamide ligand (bppCONH2) is described. The complex salts [Fe(bppCONH2)2](BF4)2 and [Fe(bppCONH2)2](ClO4)2 were synthesised and characterised by SQUID magnetometry, differential scanning calorimetry, variable temperature Raman spectroscopy and single crystal X-ray diffraction. DSC measurements of [Fe(bppCONH2)2](BF4)2 indicate a spin-crossover (SCO) transition with T↑ at 481 K and T↓ at 461 K, showing a 20 K hysteresis. DSC for the perchlorate salt shows an SCO transition with T↑ at 459 K and T↓ at 445 K with a 14 K hysteresis. For the BF4− salt analysis of low and high-spin state crystal structures at 101, 290 and 500 K, suggest stabilisation of the low spin state due to the formation of 1D hydrogen-bonded cationic chains. Variable temperature Raman studies of the BF4 salt support the presence of a high temperature SCO. It is speculated that the presence of hysteresis may be attributed to differences in the inter-molecular hydrogen bonding in the low spin and high spin states.

Item Type: Journal article
Publication Title: Dalton Transactions
Creators: Attwood, M., Akutsu, H., Martin, L., Blundell, T.J., Le Maguere, P. and Turner, S.S.
Publisher: Royal Society of Chemistry (RSC)
Date: 2 August 2021
ISSN: 1477-9226
Identifiers:
NumberType
10.1039/d1dt01743hDOI
1457035Other
Rights: This journal is © The Royal Society of Chemistry 2021. Open Access Article. Published on 02 August 2021. Downloaded on 8/16/2021 3:49:16 PM. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Divisions: Schools > School of Science and Technology
Record created by: Linda Sullivan
Date Added: 17 Aug 2021 08:06
Last Modified: 17 Aug 2021 08:06
URI: http://irep.ntu.ac.uk/id/eprint/44004

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