Studies of magnetic properties and HFEPR of octanuclear manganese single-molecule magnets

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 39; no. 42; pp. 10160 - 10168
• Main Authors: Wu, Che-Chih, Datta, Saiti, Wernsdorfer, Wolfgang, Lee, Gene-Hsian, Hill, Stephen, Yang, En-Che
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 01.01.2010
• Subjects: Cations; Crystal lattices; Electron paramagnetic resonance; Ground state; Magnetic permeability; Magnetic susceptibility; Magnetization; Manganese; Physics
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c0dt00405g

A new octanuclear manganese cluster [Mn(8)(Hpmide)(4)O(4)(EtCOO)(6)](ClO(4))(2) (1) is achieved by employing Hpmide as the ligand, and this paper examines the synthesis, X-ray structure, high-field electron paramagnetic resonance (HFEPR), magnetization hysteresis loops and magnetic susceptibilities. Complex 1 was prepared by two different methods, and hence, was crystallized in two space groups: P3(2)21 for 1a and P3(1)21 for 1b. Each molecule possesses four Mn(II) and four Mn(III) ions. The metal-oxo framework of complex 1 consists of three face-sharing cubes with manganese ions on alternate corners. The four Mn(III) cations have their Jahn-Teller elongation axes roughly parallel to the c axis of the crystal lattice. The dc magnetic susceptibility measurements reveal a spin-frustration effect in this compound. The ac magnetic susceptibilities, as well as the magnetization hysteresis measurements, clearly establish that complex 1a is a single-molecule-magnet (SMM) with a kinetic energy barrier (10.4 cm(-1)) for spin reversal. HFEPR further confirms that complex 1a is a new SMM with a magnetoanisotropy and quantized energy levels. However, interpretation of the complete set of measurements in terms of a well defined spin ground state is not possible due to the spin frustration.