Magnetic properties of transition metal complexes with 2,2′-bipyridin-5-yl t-butyl nitroxide

Complexes [Mn-11(5bpno)(3)(ClO4)(2)], [Mn-11(5bpno)(CH3OH)(2)Cl-2], [Cu-11(5bpno)(2)(ClO4)(2)], and [Cu-11(5bpno)Cl-2] were prepared, where 5bpno stands for 2,2'-bipyridin-5-yl t-butyl nitroxide. X-ray crystallographic analysis clarified that the Cu ion in [Cu(5bpno)(2)(ClO4)(2)] was tetra-coordinate with four nitrogen atoms forming two chelate rings. Magnetic measurements revealed the presence of ferromagnetic couplings in the Mn complexes, whereas the Cu complexes showed antiferromagnetic Couplings. Magnetic exchange couplings between the metal and radical spins through the intervening pyridine ring can be explained in terms of the spin-polarization mechanism. (c) 2005 Elsevier Ltd. All rights reserved.