Structure and magnetism of the first strictly dinuclear compound containing paramagnetic 3d and 5f metal ions. Major influence of the Cu-II ion coordination on the exchange Cu-II-U-IV interaction

The dinuclear compound [CuL2(py)U(acac)(2)] has been synthesized by treating [Cu(H2L2)] with U(acac)(4) (L-2 = N,N'-bis(3-hydroxysalicylidene)-2-methyl-1,2-propanediamine) and shows the antiferromagnetic Cu-U interaction; the distinct magnetic behaviour of the trinuclear complexes [(CuL2)(2)U] (antiferromagnetic) and [{CuL1(py)}U{CuL1}] (ferromagnetic) revealed the major influence of the Cu-II ion coordination on the exchange interaction (L-1 = N,N'-bis(3-hydroxysalicylidene)-2,2- dimethyl-1,3-propanediamine).