Magnetic properties of layered complexes [M(hfac)2]3(R)2, M=Mn(II) and Cu(II), with trisnitroxide radicals having various metal-radical exchange interactions

A series of new layered 2D-network complexes [M(hfac)2]3(RΔ)2 of M=Mn(II) and Cu(II) with trisnitroxide radicals RΔ has been prepared and the magnetic properties were studied. Each triradical RΔ has a quartet ground state and contributes not only to the formation of extended structures but essentially to the overall magnetism. Several exchange interactions, between M and nitroxide and intraradical nitroxide-nitroxide interactions, are responsible for the development of the characteristic magnetic properties in these heterospin systems. Depending on the nature of the interlayer interactions, they show either ferro/ferrimagnetic or antiferromagnetic long range order. The hierarchy of the different exchange interactions is established and the Mn-nitroxide and Cu-nitroxide exchange integrals are evaluated from the analysis of the temperature dependence of the paramagnetic susceptibility. With increasing intraradical exchange interaction, the complexes exhibit more pronounced 2D behaviour. (author)