Synthesis, Structures, and Magnetic Properties of Tri- and Dinuclear Copper(II)−Gadolinium(III) Complexes of Linear Oligooxime Ligands

We have designed and synthesized a new Cu2Gd heterotrinuclear complex, [LCu2Gd(OAc)3] (1), where H4L is a
bis(salen)-type tetraoxime ligand useful in the synthesis of discrete (3d)2(4f) complexes. Complex 1 crystallizes in
the triclinic system, space group P1̄, with unit cell parameters a = 12.442(4) Å, b = 13.397(3) Å, c = 13.966(4)
Å, α = 77.052(8)°, β = 88.656(10)°, γ = 77.761(8)°, and Z = 2. In the crystal structure of 1, Cu−Gd distances
are 3.3−3.5 Å, whereas the two Cu atoms are separated by 6.08 Å. The corresponding dinuclear CuGd complexes,
2 and 3, with mono(salen)-type chelate 3-MeOsalamo were also synthesized. Complex 2 crystallizes in the monoclinic
system, space group P21/c, with unit cell parameters a = 13.869(8) Å, b = 13.688(7) Å, c = 18.728(10) Å, β =
92.861(8)°, and Z = 4, and complex 3 crystallizes in the triclinic system, space group P1̄, with unit cell parameters
a = 12.319(4) Å, b = 13.989(4) Å, c = 16.774(5) Å, α = 64.699(14)°, β = 66.672(13)°, γ = 76.891(17)°, and
Z = 4. Interaction between CuII and GdIII in the dinuclear complexes 2 and 3 is ferromagnetic (J = 4.5 and 7.6
cm-1, respectively, using spin Hamiltonian H = −JSCu·SGd) as observed in the previously prepared [LCuGdX3]
complexes, where L is a salen-type chelate. Magnetic data for the Cu2Gd trinuclear complex can be reasonably
interpreted with the use of a spin Hamiltonian H = −JCuGdSCu1·SGd − JCuGdSCu2·SGd − JCuCuSCu1·SCu2 with JCuGd =
5.0 cm-1 and JCuCu = 0 cm-1. The S = 9/2 ground state resulted from the ferromagnetic interaction among the
CuII−GdIII−CuII triad was also supported by the saturation magnetization at 1.8 K.