Octanuclear Ni₄Ln₄ Coordination Aggregates from Schiff Base Anion Supports and Connecting of Two Ni₂Ln₂ Cubes: Syntheses, Structures, and Magnetic Properties

Abstract

A family of 3d–4f aggregates have been reported through guiding the dual coordination modes of ligand anion (HL−) and in situ generated ancillary bridge driven self‐assembly coordination responses toward two different types of metal ions. Reactions of lanthanide(III) nitrate (Ln=Gd, Tb, Dy, Ho and Yb), nickel(II) acetate and phenol‐based ditopic ligand anion of 2‐[{(2‐hydroxypropyl)imino}methyl]‐6‐methoxyphenol (H2L) in MeCN‐MeOH (3 : 1) mixture and LiOH provided five new octanuclear Ni‐4f coordination aggregates from two Ni2Ln2 cubanes. Single‐crystal X‐ray diffraction analysis reveals that all the members of the family are isostructural, with the central core formed from the coupling of two distorted [Ni2Ln2O4] heterometallic cubanes [Ni2Ln2(HL)2(μ3‐OH)2(OH)(OAc)4]+ (Ln=Gd (1), Tb (2), Dy (3), Ho (4) and Yb (5)). Higher coordination demand of 4f ions induced the coupling of the two cubes by (OH)(OAc)2 bridges. Variable temperature magnetic study reveals weak coupling between the Ni2+ and Ln3+ ions. For the Tb (2) and Dy (3) analogs, the compounds are SMMs without an applied dc field, whereas the Gd (1) analogue is not an SMM. The observation revealed thus that the anisotropy of the Ln3+ ions is central to display the SMM behavior within this structurally intriguing family of compounds.

Three angular Zn2Dy complexes showing the effect of remote coordination at Zn and counter ions on slow magnetic relaxation at Dy centres

“…3) ac susceptibility components of complex 2 in the 1.0 kOe applied magnetic field reveal the characteristic signals of slow magnetic relaxation below 6 K. However, only a peak tail is observed at frequencies below 1400 Hz until 2 K, suggesting that complex 2 displays characteristics of a weak SMM. 49 Complex 3 also exhibited similar frequency-dependent in-phase (Fig. S11, ESI†) and out-of-phase ( χ ′′ mol ) (Fig.…”

Synthesis and characterization of two self-assembled [Cu6Gd3] and [Cu5Dy2] complexes exhibiting the magnetocaloric effect, slow relaxation of magnetization, and anticancer activity

“…[35][36][37][38] Ligands with ONO binding sites and the aroylhydrazone skeleton can be associated with Ln III ions to obtain various target compounds which can interact with biomacromolecules like DNA and HSA. 39 Phenol function bearing ligands containing coordinating N donors from the imine group and O donors from phenol, alcohol and ether groups can be the most useful and versatile bridging agents to construct 3d-4f ion-based coordination clusters, [40][41][42][43] wherein the N atom can be utilized to trap the 3d ions selectively and the O atom is more inclined to bind the 4f ions in accordance with the SHAB principle. We were engaged in the synthetic exploration of the self-assembled versions of the reaction products resulting from the Schiff base anions and chosen 3d and 4f ions.…”

Self-assembly of Schiff base anions and the trapping of HO−, O2− and Piv− bridges in a family of Ni3Ln4 complexes: synthesis, structures and magnetic properties

“…14 So far, many such heterometallic complexes that incorporate Ni II and 4f ions of varying nuclearity are known. These include dinuclear NiLn, 15 trinuclear Ni 2 Ln 16 or Ln 2 Ni, 17 tetranuclear Ni 2 Ln 2 18 or Ni 3 Ln, 19 pentanuclear Ni 3 Ln 2 , 20 hexanuclear Ni 4 Ln 2 , 21 Ni 3 Ln 3 14 b or Ni 2 Ln 4 , 22 heptanuclear Ni 4 Ln 3 , 23 Ni 3 Ln 4 24 or Ni 6 Ln, 25 octanuclear Ni 4 Ln 4 26 or Ni 5 Ln 3 , 27 nonanuclear Ni 6 Ln 3 , 28 and higher nuclear complexes. 29 However, reports on heptanuclear Ni–Ln complexes are rare, and the Ni 3 Ln 4 topology reported in this work is unprecedented in the literature.…”