Isomorphous replacement of MII ions in MII–GdIII dimers (MII = CuII, MnII, NiII, CoII, ZnII): magnetic studies of the products

Abstract

Complexes [M^IIGd^III{pyCO(OEt)pyC(OH)(OEt)py}₃](ClO₄)₂·EtOH [M^II = Cu^II (1), Mn^II (2), Ni^II (3), Co^II (4) and Zn^II (5)] crystallize in the monoclinic Cc space group and contain one hexacoordinate M^II ion and one enneacoordinate Gd^III ion, bridged by three {pyCO(OEt)pyC(OH)(OEt)py}⁻ ligands. Magnetic susceptibility measurements indicate a ferromagnetic interaction for 1 and antiferromagnetic interactions for 2–4. Using the Ĥ = −JŜ_Gd^IIIŜ_M^II spin Hamiltonian formalism, fits to the magnetic susceptibility data yielded J values of +0.32 cm⁻¹ for 1, −1.7 cm⁻¹ for 2, and −0.22 cm⁻¹ for 3. In complex 4, the orbital contributions of Co^II precluded the determination of the magnetic coupling. The complex follows the Curie–Weiss law with θ = −2.07 K (−1.44 cm⁻¹).