Self-assembly and characterization of cyano-bridged bimetallic [Ln-Fe] and [Ln-Co] complexes (Ln = La, Pr, Nd and Sm).: Nature of the magnetic interactions between the Ln3+ and Fe3+ ions

Two structural series, including seven isomorphous heterodinuclear complexes, [Ln(DMSO)(4)(H2O)(3)(mu-CN)M(CN)(5)]center dot H2O ([La-Fe] (1), [Pr-Fe] (2), [Pr-Co] (3), [Nd-Fe] (4), [Nd-Co] (5), [Sm-Fe] (6) and [Sm-Co] (7)), and seven isostructural 2-D stairlike cyano-bridged bimetallic assemblies, [Ln(DMSO)(2)(H2O)(mu-CN)(4)M(CN)(2)](n) ([La-Fe](n) (8), [Pr-Fe](n) (9), [Pr-Co](n) (10), [Nd-Fe](n) (11), [Nd-Co](n) (12), [Sm-Fe](n) (13) and [Sm-Co](n) (14)) (DMSO = dimethylsulfoxide), have been rationally prepared by a facile approach, a ball-milling method, and characterized by X-ray diffraction and magnetic measurements. The isomorphous structures, in conjunction with the diamagnetism of the Co3+ and La3+ ions, allow an approximation to the nature of coupling between the iron(III) and lanthanide(III) ions in the Ln(3+)-Fe3+ complexes. The Ln(3+)-Fe3+ interaction is ferromagnetic for the dinuclear [Pr-Fe] (2), [Nd-Fe] (4), and [Sm-Fe] (6) systems and for the 2-D [Pr-Fe](n) (9), [Nd-Fe](n) (11), and [Sm-Fe](n) (13) assemblies.