Synthesis, characterization and magnetic properties of an oxido-bridged tetranuclear copper(II) complex

Tetrahedral M4(μ4-O) Motifs Beyond Zn: Efficient One-Pot Synthesis of Oxido-Amidate Clusters via a Transmetalation/Hydrolysis Approach

While zinc μ4-oxido-centered complexes are widely used as versatile precursors and building units of functional materials, the synthesis of their analogues based on other transition metals is highly underdeveloped. Herein, we present the first efficient systematic approach for the synthesis of homometallic [M4(μ4-O)L6]-type clusters incorporating divalent transition-metal centers, coated by bridging monoanionic organic ligands. As a proof of concept, we prepared a series of charge-neutral metal-oxido benzamidates, [M4(μ4-O) (NHCOPh)6] (M = Fe, Co, Zn), including iron(II) and cobalt(II) clusters not accessible before. The resulting complexes were characterized using elemental analysis, FTIR spectroscopy, magnetic measurements, and single-crystal X-ray diffraction. Detailed structural analysis showed interesting self-assembly of the tetrahedral clusters into 2D honeycomb-like supramolecular layers driven by hydrogen bonds in the proximal secondary coordination sphere. Moreover, we modeled the magnetic properties of new iron (II) and cobalt (II) clusters, which display a general tendency for antiferromagnetic coupling of the μ4-O/μ-benzamidate-bridged metal centers. The developed synthetic procedure is potentially easily extensible to other M(II)-oxido systems, which will likely pave the way to new oxido clusters with interesting optoelectronic and self-assembly properties and, as a result, will allow for the development of new functional materials not achievable before.

Study on the Magneto-Structural Correlation of a New Dinuclear Cobalt(II) Complex with Double μ-Phenoxo Bridges

A new μ-phenoxo-bridged dinuclear cobalt(II) complex, [Co₂(L)₂(acac)₂(H₂O)] (1), has been synthesized by employing a new ligand, (4-methyl-2-formyl-6-(((2-trifluoromethyl)phenyl)methyliminomethyl) phenol) (HL). Structural analysis of complex 1 reveals that the geometry around cobalt centers is best described as a distorted octahedron and the distance of cobalt neighbors is 3.128(0) Å. The magnetic property studies indicate that complex 1 exhibits strong spin-orbit coupling effects and weak ferromagnetic coupling between two high-spin Co(II) centers linked by double μ-O_phenoxo bridges, with J = 1.87(2) cm^-1. The studies show that not only the Co-O-Co angle affects the alignment of the cobalt spins but also the dihedral angle between the CoOCo plane and the phenyl plane plays an important role in the magnetic coupling in this [Co₂O₂] system. Thus, the small bridging angles (96.96(11) and 96.91(11)°) and the large dihedral angles between the CoOCo plane and the phenyl plane (63.0(1) and 30.6(1)°) induce intramolecular ferromagnetic exchange interaction in complex 1.

Strategic synthesis of [Cu2], [Cu4] and [Cu5] complexes: inhibition and triggering of ligand arm hydrolysis and self-aggregation by chosen ancillary bridges

A new family of Cu^II-based coordination aggregates is synthesized from HL1 with Cu(ClO₄)₂·6H₂O in the absence and presence of a group of carboxylates.

Unique trapping of paddlewheel copper(ii) carboxylate by ligand-bound {Cu2} fragments for [Cu6] assembly

Trapping of paddlewheel {Cu₂(carboxylate)₄} by ligand-bound {Cu₂(μ-H₂L)}³⁺ units resulted in dumbbell-shaped [Cu₆] complexes modulating the tetracarboxylate bridged Cu⋯Cu separations.

Two types of nitrito support for μ4-oxido-bridged [Cu4] complexes: synthesis, crystal structures, magnetic properties and DFT analysis

In situ generated NO₂⁻ and externally added NO₂⁻ and AcO⁻ ions have been utilized for the isolation of μ₄-oxido-bridged Cu₄ aggregates showing magnetic coupling which can be rationalized by DFT calculations.

Mono- and tetra-nuclear copper complexes bearing bis(imino)phenoxide derived ligands: catalytic evaluation for benzene oxidation and ROP of ε-caprolactone

Mono- and tetra-nuclear copper bis(imino)phenoxide complexes have been evaluated as catalysts for benzene oxidation and ROP of ε-caprolactone.

Novel tetranuclear Ni(II) Schiff base complex containing Ni4O4 cubane core: synthesis, X-ray structure, spectra and magnetic properties

Novel tetranuclear nickel(II) Schiff base complex having symmetric Ni4O4 cubane-core, [Ni4O2(OAc)2(L)2] (1) has been synthesized. Single crystal of the complex exhibits four nickel atoms in the alternate corner of the cubane and other four sites are occupied by phenolate-O and μ3-O(2-). Variable temperature magnetic moment data suggests the Ni centres are weakly antiferromagnetically coupled with J1=-4.82cm(-1) and J2=-4.83cm(-1). The electronic spectra, emission properties and life time measurement of ligand, HL and complex 1 have been studied.