Spin Frustrated Pyrazolato Triangular CuII Complex: Structure and Magnetic Properties, an Overview

The synthesis and structural characterization of a new triangular Cu-3-mu 3OH pyrazolato complex of formula, [Cu-3(mu(3)-OH)(pz)(3)(Hpz)(3)][BF4](2) (1-Cu-3), Hpz = pyrazole, is presented. The triangular unit forms a quasi-isosceles triangle with Cu-Cu distances of 3.3739(9), 3.3571(9), and 3.370(1) & ANGS;. This complex is isostructural to the hexanuclear complex [Cu-3(mu(3)-OH)(pz)(3)(Hpz)(3)](ClO4)(2)](2) (QOPJIP). A comparative structural analysis with other reported triangular Cu-3-mu 3OH pyrazolato complexes has been carried out, showing that, depending on the pyrazolato derivative, an auxiliary ligand or counter-anion can affect the nuclearity and/or the dimensionality of the system. The magnetic properties of 1-Cu-3 are analyzed using experimental data and DFT calculation. A detailed analysis was performed on the magnetic properties, comparing experimental and theoretical data of other molecular triangular Cu-3-mu 3OH complexes, showing that the displacement of the mu(3)-OH- from the Cu-3 plane, together with the type of organic ligands, influences the nature of the magnetic exchange interaction between the spin-carrier centers, since it affects the overlap of the magnetic orbitals involved in the exchange pathways. Finally, a detailed comparison of the magnetic properties of 1-Cu-3 and QOPJIP was carried out, which allowed us to understand the differences in their magnetic properties.