Abstract
Two anionic complexes, {[Cu3(µ3-OH)(µ-4-Ph-pz)3Cl3]2[Cu(4-Ph-pzH)4](µ-Cl)2}2− (1) and [Cu3(µ3-OH)(µ-pz)3(µ1,1-N3)2(N3)]− (2), crystallize as one-dimensional polymers, held together by weak Cu-(µ-Cl) and Cu-(µ-N3) interactions, respectively. Variable temperature magnetic susceptibility analyses determined the dominant antiferromagnetic intra-Cu3 exchange parameters in the solid state for both complexes, whereas the weak ferromagnetic inter-Cu3 interactions manifested also in the solid state EPR spectra, are absent in the corresponding frozen solution spectra. DFT calculations were employed to support the results of the magnetic susceptibility analyses.
Highlights
We present a structural, magnetic susceptibility and EPR study of two supramolecular assemblies of metallacyclic CuII pyrazolates with Cu3(μ3-OH) cores
Weak intramolecular antiferromagnetic exchange is active within a molecule containing two isolated CuII centers separated by a K+ ion, whereas relatively strong ferromagnetic interactions were found between adjacent units, along a supramolecular pathway [3]
The theoretical calculations based on density functional theory (DFT) were done with ORCA 4.1 package [24] using B3LYP hybrid functional [25,26,27] accounting for relativistic effects with ZORA Hamiltonian and respective ZORA-def2-TZVP basis set for Cu, N, O, Cl atoms and ZORA-def2-SVP basis set for C and H atoms [28]
Summary
We present a structural, magnetic susceptibility and EPR study of two supramolecular assemblies of metallacyclic CuII pyrazolates with Cu3(μ3-OH) cores. The focus of this work is the elucidation of weak intermolecular interactions manifested in the magnetic properties and EPR spectra of the supramolecular assemblies. Weak intramolecular antiferromagnetic exchange is active within a molecule containing two isolated CuII centers separated by a K+ ion, whereas relatively strong ferromagnetic interactions were found between adjacent units, along a supramolecular pathway [3]. In yet another dinuclear CuII complex with chelating 2-hydroxy-1,10-phenanthroline and bridging thiocyanate ligands, it was shown that an intermolecular ferromagnetic exchange was facilitated by π–π interactions between phenanthroline ligands [4,5,6]. Continuing along the same lines, we report here the structure and magnetochemical studies of a heptanuclear CuII assembly employing 4-phenyl-pyrazole ligands and of a polymeric structure containing Cu3N6 metallacycles with terminal and bridging azido ligands
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