Synthesis, Structure, and Magnetic Properties of a Family of Heterometallic Pentanuclear [Co 4 Ln] (Ln = Gd III , Dy III , Tb III , and Ho III ) Assemblies

Slow magnetic relaxation in a homo dinuclear Dy(iii) complex in a pentagonal bipyramidal geometry

We hereby report a dinuclear Dy(iii) complex, [Dy(LH₃)Cl₂]₂·2Et₂O (1) (LH₄ = 2,3-dihydroxybenzylidene)-2-(hydroxyimino)propanehydrazide where both the metal centres are in a pentagonal bipyramidal (PBP) geometry with the axial positions being occupied by negatively charged Cl^- ions. The complex as well as it's 10% diluted analogue (1₁₀) do not show zero-field SMM behaviour. However, in the presence of small optimum dc fields the slow relaxation of magnetization was displayed. The effective energy barrier for 1₁₀ at 800 Oe of applied field was extracted as 83(17) K with τ₀ = 2(4) × 10^-12 s. Through a combined experimental and ab initio electronic structure calculations studies we have thoroughly analysed the role of the ligand field around the Dy(iii), present in pentagonal bipyramidal geometry, in contributing to the slow relaxation of magnetization.

Bis-phenoxido and bis-acetato bridged heteronuclear {Co(III)Dy(III)} single molecule magnets with two slow relaxation branches

Two bis-μ-phenoxido-bis-μ-acetato heterobimetallic {Co(III)Dy(III)} complexes and , formulated as [Co(III)Dy(III)L(μ-OAc)2(NO3)2] derived from the comparable hexadentate Schiff bases N,N'-ethylenebis(3-ethoxysalicylaldimine) and N,N'-ethylenebis(3-methoxysalicylaldimine) were synthesized and X-ray structure analysis confirms their nearly identical structures. These are the first examples of bis(μ-phenoxido)-bis(μ-carboxylato) {Co(III)Dy(III)} systems. The AC susceptibility measurements show that both complexes exhibit a field-induced slow magnetic relaxation with two relaxation branches. While the high-frequency process spans the usual range of the relaxation time for analogous single molecule magnets (τ0 ∼ 10(-7) s), the low-frequency branch is as slow as τ ∼ 0.1 s at T = 1.9 K and B = 0.2 T.

Isoskeletal Schiff base polynuclear coordination clusters: synthetic and theoretical aspects

This work addresses and enlightens synthetic aspects derived from our effort to systematically construct isoskeletal tetranuclear coordination clusters (CCs) of the general formula [TR₂Ln₂(LX)₄(NO₃)₂(solv)₂] possessing a specific defected dicubane topology.

Pentanuclear [2.2] spirocyclic lanthanide(iii) complexes: slow magnetic relaxation of the DyIII analogue

A series of [2.2] spirocyclic complexes [Ln₅(LH)₄(η¹-Piv)(η²-Piv)₃(μ₂–η² η¹Piv)₂(H₂O)]·Cl (Ln = Dy^III, Tb^III and Ho^III) were synthesized. Magnetic analysis reveals that the Dy^III analogue showed slow relaxation of magnetization.