Trigonal to pentagonal bipyramidal coordination switching in a Co(II) single-ion magnet

Hay, M. A., McMonagle, C. J., Wilson, C. , Probert, M. R. and Murrie, M. (2019) Trigonal to pentagonal bipyramidal coordination switching in a Co(II) single-ion magnet. Inorganic Chemistry, 58(15), pp. 9691-9697. (doi: 10.1021/acs.inorgchem.9b00515) (PMID:31328921)

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In molecular magnetism and single-ion magnets in particular, the observation of slow relaxation of the magnetization is intimately linked to the coordination environment of the metal center. Such systems typically have blocking temperatures well below that of liquid nitrogen, and therefore detailed magnetic characterization is usually carried out at very low temperatures. Despite this, there has been little advantage taken of ultralow temperature single-crystal X-ray diffraction techniques that could provide a full understanding of the crystal structure in the same temperature regime where slow magnetic relaxation occurs. Here, we present a systematic variable temperature single crystal X-ray diffraction study of [CoII(NO3)3(H2O)(HDABCO)] (1) {DABCO = 1,4-diazabicyclo[2.2.2]octane} conducted between 295 to 4 K. A reversible and robust disorder-to-order, single-crystal to single-crystal phase transition was identified, which accompanied a switching of the coordination geometry around the central Co(II) from 5- to 7-coordinate below 140 K. The magnetic properties were investigated, revealing slow relaxation of the magnetization arising from a large easy-plane magnetic anisotropy (+D) in the Co(II) pentagonal bipyramidal environment observed at low temperatures. This study highlights the importance of conducting thorough low temperature crystallographic studies, particularly where magnetic characterization is carried out at such low temperatures.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Wilson, Dr Claire and Hay, Ms Moya Anne and Murrie, Professor Mark
Authors: Hay, M. A., McMonagle, C. J., Wilson, C., Probert, M. R., and Murrie, M.
College/School:College of Science and Engineering
College of Science and Engineering > School of Chemistry
Journal Name:Inorganic Chemistry
Publisher:American Chemical Society
ISSN (Online):1520-510X
Published Online:22 July 2019
Copyright Holders:Copyright © 2019 American Chemical Society
First Published:First published in Inorganic Chemistry 58(15):9691-9697
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
696981Putting the Squeeze on Molecule-Based MagnetsMark MurrieEngineering and Physical Sciences Research Council (EPSRC)EP/N01331X/1CHEM - CHEMISTRY
701101EPSRC 2015 DTPMary Beth KneafseyEngineering and Physical Sciences Research Council (EPSRC)EP/M508056/1R&I - RESEARCH STRATEGY & INNOVATION