High pressure induced spin changes and magneto-structural correlations in hexametallic SMMs

DOI: 10.1039/b902485a

Authors: Alessandro Prescimone (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK) , Constantinos J. Milios (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK) , Javier Sanchez-benitez (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK) , Konstantin V. Kamenev (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK) , Claudia Loose (nst. Fuer Theoretische Physik, TU Bergakademie Freiberg, Germany) , Jens Kortus (nst. Fuer Theoretische Physik, TU Bergakademie Freiberg, Germany) , Stephen Moggach (The University of Edinburgh) , Mark Murrie (Department of Chemistry, University of Glasgow, U.K.) , John Warren (University of Liverpool; Daresbury) , Alistair Lennie (Diamond Light Source) , Simon Parsons (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK) , Euan K. Brechin (School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, Edinburgh, UK)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Dalton Transactions , VOL (25) , PAGES 4858-4867

State: Published (Approved)
Published: January 2009

Abstract: The first combined high pressure single-crystal X-ray diffraction and high pressure magnetism study of two polymetallic clusters is presented in an attempt to correlate the observed changes in structure with changes in magnetic response without the need for changes in external ligation. At 1.5 GPa the structure of [Mn6O2(Et-sao)6(O2CPh(Me)2)2(EtOH)6] (1; Et-saoH2 = 2-hydroxyphenylpropanone)—a single molecule magnet (SMM) with an effective anisotropy barrier of ∼86 K—and of [Mn6O2(Et-sao)6(O2C-naphth)2(EtOH)4(H2O)2] 2 both undergo significant structural distortions of their metallic skeletons, which has a direct effect upon the observed magnetic response. The application of hydrostatic pressure on the two compounds (up to 1.5 GPa) flattens the Mn–N–O–Mn torsion angles weakening the magnetic exchange between the metal centres. In both compounds one interaction switches from ferro- to antiferromagnetic, with the Jahn–Teller (JT) axes compressing (on average) and re-aligning differently with respect to the plane of the three metal centres. High pressure dc χMT plots display a gradual decrease in the low temperature peak height and slope, simulations showing a decrease in |J| with increasing pressure with a second antiferromagnetic J value required to simulate the data. The “ground states” change from S = 12 to S = 11 for 1 and to S = 10 for 2. Magnetisation data for both 1 and 2 suggest a small decrease in |D|, while out-of-phase (χM//) ac data show a large decrease in the effective energy barrier for magnetisation reversal.

Subject Areas: Chemistry

Facility: Daresbury Laboratory

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