Dreiser, J.; Pedersen, K.S.; Schnegg, A.; Holldack, K.; Nehrkorn, J.; Sigrist, M.; Tregenna-Piggott, P.; Mutka, H.; Weihe, H.; Mironov, V.S.; Bendix, J.; Waldmann, O.: Anisotropic Exchange Coupling in the Single-Molecule Magnets (NEt4)[MnIII2(5-Brsalen)2(MeOH)2MIII(CN)6] (M = Ru,Os). Chemistry - A European Journal 19 (2013), p. 3693-3701
10.1002/chem.201203781

Abstract:
We have investigated the single-molecule magnets (NEt4)[Mn2(5 Brsalen)2(MeOH)2M(CN)6], with M = Os (1) and Ru (2) by frequency-domain Fourier-transform Terahertz-EPR, inelastic neutron scattering and SQUID magnetometry. The unique combination of all three techniques delivers unambigous experimental evidence for the existence of strongly anisotropic magnetic exchange coupling between MnIII and RuIII or OsIII ions, respectively. We analyze our data using a spin-Hamiltonian parameterization, yielding excellent agreement with all experimental data. Furthermore, analytical calculations show that the observed exchange anisotropy is due to the bent geometry encountered in both 1 and 2, whereas a linear geometry would lead to an Ising-type exchange coupling.