Synthesis, Crystal Structure, Spectroscopic and Magnetically Study of Two Copper(II) Complexes with Pyrazole Ligand

The synthesis and characterization of two new Cu-II complexes with pyrazole ligands formulated as [Cu-3(mu-Pz)(3)(mu(3)-OH)(Pz)(2)Cl-2][Cu-3(mu-Pz)(3)(mu(3)-OH)(Pz)(2)Cl-2(DMF)]center dot 2DMF (1) and [Cu-3(mu-DMPz)(3)(DMF)(4)(OAc)(mu(3)-OH)(H2O)](+)[Cu-3(mu-DMPz)(3)(DMF)-(NCS)(3)(mu(3)-OH)](-) (2) (where Pz = 1H-pyrazole and DMPz = 3,5-dimethyl- 1H-pyrazole) are reported. The compounds were prepared by the reaction of zero valent copper metal and Pz or DMPz in the dimethylformamide solution in the presence of the different additional components (chloride or thiocyanate ligands). The crystal structures of both compounds were determined by single-crystal X-ray diffraction analy-sis. Both compounds 1 and 2 are hexanuclear clusters comprising from neutral (1) or charged (2) trinuclear triangular fragments Cu-3(mu(3)-OH)(mu-Pz)(3) of inverse azametallacrowns aza9-MCCuII-3 topology. Nevertheless, they exhibit relevant differences in their molecular structures. The magnetic measurement shows the isotropic antiferromagnetic interaction in 2 with J(1) = -140 cm(-1) for the cationic and J(2) = -109 cm(-1) (-2JS(i)center dot S-j model) for the anionic part of the molecule above 100 K and significant influence of antisymmetric exchange at lower temperatures.