The building of multidimensional magnetic materials obtained with the molecular precursor [Cu(opba)](2-) is described. The reaction with other paramagnetic species (3d or 4f metal ions, organic radicals) yielded one-dimensional, two-dimensional, and interlocked networks. The magnetic properties of these systems are reviewed using polarized neutron diffraction and magnetic measurements. It is shown that the spin density maps give a precise description of the ground state of such molecular magnetic species. Moreover, different long-range magnetic orderings (antiferro-, ferri-, and ferromagnetic) have been obtained.