In honor of Professor Pierre Braunstein.
AbstractThe single-crystal X-ray structures of two new linear trinuclear copper(II) complexes of 3,5-pyrazoledicarboxylic acid ( (2), with Me 2 en is N ,N -dimethylethylenediamine. Both complexes are trinuclear and have been obtained from a precursor ligand, through copper-induced amide hydrolysis. In 1, the central copper ion is in a distorted square-planar environment and the two outer copper ions are in a distorted square-pyramidal environment. All three copper ions in 2 are six-coordinated in an elongated octahedral environment. A weak, broad EPR signal centered around g 0/3.5, indicative for an S0/3/2 state, is observed and confirms both complexes to be trinuclear. Magnetic susceptibility measurements of 1 and 2 from 4 to 300 K indicate a weak anti-ferromagnetic exchange coupling, with J values of (/15 and (/19 cm (1 , respectively. #