Статья

Synthesis and characterisation of a Ni4 single-molecule magnet with S4 symmetry

Alan FergusonWestCHEM, Department of Chemistry, University of Glasgow, University Avenue, Glasgow, UK G12 8QQJ. M. LawrenceDepartment of Physics, University of Florida, Gainsville, FLAndrew ParkinWestCHEM, Department of Chemistry, University of Glasgow, University Avenue, G12 8QQ, Glasgow, UKJ. Sánchez-Benı́tezSchool of Engineering and Electronics and Centre for Science at Extreme Conditions, University of Edinburgh, West Mains Road, Edinburgh, UKKonstantin V. KamenevSchool of Engineering and Electronics and Centre for Science at Extreme Conditions, University of Edinburgh, West Mains Road, Edinburgh, UKEuan K. BrechinSchool of Chemistry, University of Edinburgh, West Mains Road, Edinburgh, UKWolfgang WernsdorferInstitut Néel, CNRS & University J. Fourier, Grenoble Cedex 9, FranceStephen HillDepartment of Physics, University of Florida, Gainsville, FLMark MurrieWestCHEM, Department of Chemistry, University of Glasgow, University Avenue, G12 8QQ, Glasgow, UK

2008en

ABI

Аннотация

[Ni4Cl4(HL)4] () {H2L=HN(CH2CH2OH)2} has S4 symmetry and crystallises in the tetragonal space group I4(1)/a. Two exchange couplings are observed between the four Ni(II) centres, with J1=7.29 cm(-1) and J2=-2.08 cm(-1), leading to an S=4 ground state. The Ni4 complex shows the onset of frequency dependent signals in the out-of-phase ac susceptibility below 3 K. In single-crystal measurements carried out using a micro-SQUID, hysteresis loops are observed below 0.5 K, confirming that shows slow relaxation of magnetisation. The loops are temperature dependent but only weakly sweep rate dependent due to the presence of small intermolecular interactions, which hinder quantum tunnelling. This exchange bias between Ni4 molecules is also seen in high-frequency high-field EPR measurements, which give the parameters D=-0.75 cm(-1), B4 degrees=-6.7x10(-5) cm(-1) and gz=2.275.

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Идентификаторы

DOI: 10.1039/b807447j

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