For mononuclear 1, the room temperature susceptibility-temperature product is χT = 3.41 cm 3 K mol -1 . Upon lowering the temperature, χT remains essentially constant down to 100 K and then decreases slowly, before decreasing more strongly below 3 K. For the dinuclear complex 2, the room temperature susceptibility-temperature product is χT = 6.99 cm 3 K mol -1