PUB - Publikationen an der Universität Bielefeld

Two families of copper lanthanide phosphonate clusters have been obtained through reaction of [Cu-2((O2CBu)-Bu-t)(4)((HO2CBu)-Bu-t)(2)] and either Ln(NO3)(3)center dot nH(2)O or [Ln(2)(O(2)C(t)nu)(6)((HO2CBu)-Bu-t)(6)} and tert-butylphosphonic acid or an amino-functionalized phosphonic acid. The clusters, with general formula [Cu(MeCN)(4)][Cu(3)Ln(9)(mu(3)-OH)(7)((O3PBu)-Bu-t)(6)((O2CBu)-Bu-t)(15)} and [Cu(6)Ln(6)(mu(3)-OH)(6)(O3PC(NH2)Me-2)(6)((O2CBu)-Bu-t)(12)}, were structurally characterized through single crystal X-ray diffraction and possess highly symmetric metal cores with approximately C-3v and D-3h point symmetry, respectively. We have investigated the possible application of the isotropic analogues in magnetic cooling, where we were able to observe that up to around 70% of the theoretical magnetic entropy change is obtained. Simulation of the magnetic data shows antiferromagnetic coupling between the spin centers, which explains the magnetic entropy value observed.