Published in J. Am. Chem. Soc. 2007, 129 , 10306-10307.

A Definitive Determination of Zero-Field Splitting and Exchange Interactions in a Ni(II) Dimer: Investigation of [Ni2(en)4Cl2]Cl2 Using Magnetization and Tunable-Frequency High-Field EPRR. Herchel (1), R. Boča (2), J. Krzystek (3), A. Ozarowski (3), M. Durán (4), and J. van Slageren (4)(1) Department of Inorganic Chemistry, Palacký University, CZ-77147 Olomouc, Czech Republic(2) Institute of Inorganic Chemistry, Slovak Technical University, SK-812 37 Bratislava, Slovakia (3) National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA(4) 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany Understanding the origin of zero-field splitting (ZFS) in molecular magnets is of great importance, because the ZFS determines many of their fundamental properties. The aim of this work has thus been to elucidate the microscopic origin of ZFS in dinuclear exchange coupled systems with large anisotropies exemplified by a classic complex bis(μ-chloro)tetrakis(ethylenediamine) dinickel(II) dichloride, [Ni2(en)4Cl2]Cl2 (1). In this class of complexes the single-ion anisotropy is comparable with exchange coupling constants. Figure 3. The 2-D field vs. frequency map of EPR resonances in 1. The curves were calculated using the same parameters as those used for simulating magnetic properties in Fig. 2. We developed a model that allowed us to take into account simultaneously the single-ion anisotropy, isotropic and asymmetric exchange in calculating the ZFS. Calculations using this model very successfully reproduced the experimental data set (Figs. 2 & 3) Our results point to the importance of asymmetric exchange, which is often neglected in similar systems. Figure 1. Structure of the [Ni2(en)4Cl2]2+ ion. Figure 2. Magnetic properties of 1. Left: temperature dependence of the effective magnetic moment; right: field dependence of magnetization at T = 2.0 and 4.6 K. Published in J. Am. Chem. Soc.2007, 129, 10306-10307.

Published in J. Am. Chem. Soc. 2007, 129 , 10306-10307.

Published in J. Am. Chem. Soc. 2007, 129 , 10306-10307.

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Bosques et al. J Am Chem Soc. 2004, 14, 126(27): 8422- 8425 Presented by Anoop Mayampurath

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