Structure and magnetic properties of 3d-4f heterometallic complexes containing di-2-pyridyl ketoximate: An approach to single-molecule magnets

[{Ln(hfac)(3)}(2){Ni(dpk)(2)(phen)}] (1Ln) and [{Ln(hfac)(3)}(2){Ni(dpk)(2)(py)(2)}] (2Ln) were synthesized and characterized, where dpk = di-2-pyridyl ketoxmate and Ln = La, Tb, Dy, Ho, Er. The N-0 groups from dpk bridged the central nickel(11) ion and terminal lanthanicle(111) ions, giving a linear trinuclear array. Dc magnetic susceptibility measurements revealed that they did not possess appreciable intramolecular ferromagnetic or ferrimagnetic interaction. Ac magnetic susceptibility measurements clarified that frequency dependence of out-of-phase ac susceptibility was observed only for Dy derivatives 1Dy and 2Dy, which is regarded as an indication of single-molecule magnets. (c) 2005 Elsevier Ltd. All rights reserved.