Synthesis and properties of new molecule-based magnets containing Mn(II), Cu(II) and nitronyl nitroxide radical cation

In this work, we describe the synthesis of two new copper(II) compounds, (Pr-Rad)(2) [Cu(opba)].H2O (1) and (Bu-Rad)(2)[Cu(opba)].2H(2)O (2) where opba stands for orthophenylenebis(oxamato) and R-Rad(+) are nitronyl nitroxide radical cations. From 1 and 2, two new molecule-based magnets [Pr-Rad](2)[Mn-2{Cu(opba)}(3)].3.3DMSO.5H(2)O (3) and [Bu-Rad](2) [Mn-2{Cu(opba)}(3)].3DMSO.6H(2)O (4) were obtained, respectively. The magnetic properties of precursors 1 and 2 show the presence of ferromagnetic interaction between the radical cations with copper(II), in the temperature range of 20-300 K. The magnets 3 and 4 exhibit spontaneous magnetization at critical temperatures, T-c, of 23 K and 24 K, respectively.