Synthesis, structure, and physical properties of new rare earth ferrocenoylacetonates

Abstract

New ferrocenoylacetonate complexes of several rare earth elements, [Ln(fca)3(bpy)]·MeC6H5 (Ln = Pr (), Eu (), Gd (), Tb (), Dy (), Ho (), Y (); bpy - 2,2'-bipyridine; Hfca - FcCOCH2COMe) as well as scandium ferrocenoylacetonate [Sc(fca)3]·0.5MeC6H5 (), were synthesized and characterized by single crystal X-ray diffraction analysis. In the crystal lattice of the isostructural complexes , two [Ln(fca)3(bpy)] molecules form a pair due to stacking interactions between the bpy ligands. The Ln(3+) ions are coordinated in a square antiprism geometry with a coordination number of 8. The Sc(3+) ions in complex are coordinated in an octahedral geometry. Thermolysis of complexes was studied under air and argon atmospheres; in the first case, it affords perovskites LnFeO3 as one of the products. Complexes display single-molecule magnet properties, and the effective relaxation barrier for the Dy complex , was found to be Δeff/kB = 241 K, which is one of the highest values obtained for a mononuclear β-diketonate lanthanide complex.

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

“…The magnetic behavior of complex 8 (Eu III ‐V IV ) is typical of the known mononuclear, polynuclear, and polymeric Eu III complexes with additional contribution from V IV . In the weak magnetic‐field approximation, the theoretical temperature dependence of magnetic susceptibility can be calculated using the Van Vleck equation , .…”

Magnetic Behavior of Carboxylate and β-Diketonate Lanthanide Complexes Containing Stable Organometallic Moieties in the Core-Forming Ligand

“…The coordination number of Ln 3+ is seven, which is a comparatively small value for lanthanide complexes ( Figure 5). A number of hitherto unknown ferrocenoylacetonate complexes of rare earth elements, [Ln(fca)3(bpy)]•MeC6H5 (Ln = Pr, Eu, Gd, Tb, Dy, Ho (fca = Fс(CO)CH(CO)Me; bpy = 2,2′-bipyridyl)) ( Figure 6) [24] and [Ln(fca)2(NO3)(bpy)]•nMeC6H5 (Ln = Sm, Eu, Dy, Er, Yb), were synthesized and characterized by X-ray single crystal analysis [25].…”

“…6H2O and acetylacetonate Dy(acac)3•3H2O, from Alfa Aesar (Heysham, Lancashire, UK), cymantrene from Aldrich (St. Louls, MO, USA), acetylferrocene (Alfa Aesar, 97%) and solvents (MeOH, DMSO, C6H5Me, CHCl3, C2H5OH) from Alfa Aesar. To give a fuller picture, we also present our data [24] for ferrocenoylacetonate [Dy(fca) 3 (bpy)]·MeC 6 H 5 (7). The structure of 7 contains the [Dy(fca) 3 (bpy)] complex ( Figure 6) and solvate molecules of MeC 6 H 5 .…”

“…Nevertheless, an attempt to extrapolate the Arrhenius behavior above 10 K leads to a rough estimation of the SMM energy gap of about 42 K, with a pre-exponential factor of 4.3 × 10 −7 s. The value of τ0, which is at least four orders of magnitude larger than expected for typical vibrations of the network, further confirms that the estimation value of ΔE/kB should be considered as a lower limit of the actual energy barrier for the thermally-activated relaxation process in 6. To give a fuller picture, we also present our data [24] for ferrocenoylacetonate [Dy(fca)3(bpy)]•MeC6H5 (7). The structure of 7 contains the [Dy(fca)3(bpy)] complex ( Figure 6) and solvate molecules of MeC6H5.…”

“…Thus, we proposed methods for the synthesis of new compounds, determined their molecular and crystal structures, studied their thermal behavior, as well as luminescent properties for Eu derivatives [15][16][17][18][19][20][21][22][23][24][25], but a detailed study of the magnetic behavior of some of the complexes was not carried out.…”