Experimental Evidence for the Participation of 5d Gd^IIIOrbitals in the Magnetic Interaction in Ni−Gd Complexes

Abstract

The syntheses, structural determinations, and magnetic studies of two trinuclear Ni-Gd-Ni complexes are described. The structural studies demonstrate that the two complexes present a linear arrangement of the Ni and Gd ions, with Ni ions in slightly distorted square-pyramidal or octahedral environments in complexes 1 and 2, respectively. The Ni and Gd ions are linked by two or three phenoxo bridges, so that complexes 1 and 2 present edge-sharing or face-sharing bridging cores. Ferromagnetic interactions operate in these complexes. While a unique J parameter is able to fit the magnetic data of complex 2, two very different J constants are needed for 1. This result is at first sight surprising, for the structural data of the two Ni-O(2)-Gd cores in complex 1 are quite similar (similar Ni-O and Gd-O bond lengths, similar angles, and dihedral angles), the only difference coming from the angle between the planes defined by the Gd ion and the two bridging phenoxo oxygen atoms of each Ni-O(2)-Gd half core. This latter magnetic behavior can be considered as a signature for the participation of 5d Gd(III) orbitals in the exchange interaction mechanism and can explain why edge-sharing complexes have larger J parameters than face-sharing complexes.

Analysis of the Role of Peripheral Ligands Coordinated to ZnII in Enhancing the Energy Barrier in Luminescent Linear Trinuclear Zn‐Dy‐Zn Single‐Molecule Magnets

“…The three water molecules point in the same direction, with O-Zn-Dy-O torsion angles equal to 17.0(1) and 15.9(1)8 in the Dy1 molecule and À19.9(2) and À12.3(2)8 in the Dy2 molecule.T he six-membered diamino rings appear in ac hair conformation after lanthanide complexation, as in the equivalent trinuclearN i-Ln-Ni complexes. [29] The LZn moieties are not planar, they take an umbrellaf orm with the water mol-ecule pointing above. The related Zn···Dys eparations are equal to 3.5445(6) and 3.5756(6) i nt he Dy1 molecule and to 3.5535(6)a nd 3.5669(6) i nt he Dy2 molecule.…”

Structural and Magnetic Study of a Trinuclear MnII–GdIII–MnII Complex

“…This is why we observe a weaker J Mn,Gd interaction: 0.78 cm -1 compared to the 4.8 cm -1 value for J Ni,Gd . [29] In order to understand why two different J Mn,Gd interactions may operate, we shall keep in mind that we previously found a relationship between the J values and the dihedral angles involving the CuOO and GdOO planes of the bridging CuOOGd core in Cu-Gd complexes. [30] The largest values, around 11 cm -1 , were found for planar cores corresponding to dihedral angles around 0°.…”

The First Series of Heterometallic LnIII‐VIV Complexes Based on Substituted Malonic Acid Anions: Synthesis, Structure and Magnetic Properties

“…Complexes of 3d‐4f metals are considered as good candidates for SMMs due to high anisotropy of some lanthanide ions (Tb III , Dy III , Ho III , Er III , Tm III , Yb III ) and ferromagnetic coupling observed, for example, between Cu II ‐Ln III and Ni II ‐Ln III ions. [3a], [3b], [3g], The majority of known 3d‐4f complexes contain Cr III , Mn II , Fe III ,[3b], [3h], Co II ,[3l], Ni II ,[3b], [3d], [3k], [4d], [4c], or Cu II ions. [3a], [3e], [3g], [4a], [4b], [4c], Meanwhile 3d‐4f compounds containing a vanadyl ion V IV O 2+ as the 3d center with a single 3d electron ( S = 1 / 2 ) are quite rare, although they may provide insight into the mechanism of spin–spin exchange interactions.…”