Unprecedented formation of a doubly bridged μ-peroxo-μ-pyrazolyldicarboxylato-dicobalt(III) complex

The reaction of an aqueous solution containing Co(ClO 4 ) 2 , di(2-pyridymethyl)amine (DPA) and 3,5-pyrazole dicarboxylate anion (Hpzdc 2 − ) afforded the unprecedented diamagnetic dicobalt(III)-peroxo complex [Co 2 (DPA) 2 (μ-pzdc)(μ-η 1 :η 1 -O 2 )]ClO 4 ·3H 2 O ( 1 ) where the pyrazole group was fully deprotonated. The complex was structurally characterized by IR and UV–vis spectroscopy. X-ray crystal structure of 1 reveals the existence of the doubly bridged nature of cis -μ-η 1 :η 1 -peroxo (end-on) and the dicarboxylato pyrazole. The peroxo O–O and the Co⋯Co distances are 1.406(3) and 3.7632(5) A, respectively, and the Co(III) centers are almost co-planar with the pzdc anion.