Two New Diphenoxo‐Bridged Discrete Dinuclear CuIIGdIII Compounds with Cyclic Diimino Moieties: Syntheses, Structures, and Magnetic Properties

Abstract

AbstractTwo Schiff base compartmental ligands, H2L1 and H2L2, derived from the condensation of 3‐ethoxysalicylaldehyde with 1,2‐diaminocyclohexane and orthophenylenediamine, respectively, have been utilized to isolate two diphenoxo‐bridged discrete dinuclear CuIIGdIII complexes, [CuII(H2O)L1GdIII(NO3)3] (3) and [CuIIL2GdIII(NO3)3] (4). This is the first report on the 3d‐4f compounds derived from compartmental Schiff base ligands with cyclic diamines. The compounds 3 and 4 crystallize in the triclinic P and orthorhombic Pna2(1) space groups, respectively, with the following unit cell parameters – 3: a = 8.8713(2) Å, b = 12.8399(3) Å, c = 14.0067(3) Å, α = 80.6649(5)°, β = 77.4059(5)°, γ = 76.8879(5)°, and Z = 2; 4: a = 9.2210(1) Å, b = 16.5407(2) Å, c = 19.9248(4) Å, and Z = 4. Structural analysis reveals that both are discrete dinuclear complexes. In 3, one water molecule is coordinated to the copper(II) ion to result in a square‐pyramidal coordination geometry, while the geometry of the coppe(II) center in 4 is square planar. In both complexes, the gadolinium(III) center has an O10 coordination environment. In contrast to expectation, although the N2O2 cavity affords a better planar environment for the copper(II) center in 4, the bridging moiety in complex 3 is more planar than that in 4 or in most of the previously reported examples (the dihedral angle between two CuO2Gd planes: 2.1° for 3 and 7.1° for 4). Variable‐temperature and variable‐field magnetic measurements reveal that the metal centers in both the complexes are ferromagnetically coupled (J values: 6.3 cm–1 for 3 and 5.4 cm–1 for 4; H = –2JSCu·SGd). Interestingly, complex 3 exhibits strongest ferromagnetic interaction among the related compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)