*Article* **Supramolecular Assemblies of Trinuclear Copper(II)-Pyrazolato Units: A Structural, Magnetic and EPR Study**

### **Kaige Shi 1, Logesh Mathivathanan 1, Radovan Herchel 2,\*, Athanassios K. Boudalis 3,\* and Raphael G. Raptis 1,\***


Received: 27 May 2020; Accepted: 17 June 2020; Published: 1 July 2020

**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(<sup>μ</sup>1,1-N3)2(N3)]<sup>−</sup> (**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.

**Keywords:** copper(II) complexes; pyrazolato ligands; supramolecular assembly; X-ray crystallography; magnetic susceptibility; EPR spectroscopy; isotropic exchange; antisymmetric exchange; dipolar interaction; DFT calculations
