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

The reaction of an aqueous solution containing Co(ClO4)2, di(2-pyridymethyl)amine (DPA) and 3,5-pyrazole dicarboxylate anion (Hpzdc2 −) afforded the unprecedented diamagnetic dicobalt(III)-peroxo complex [Co2(DPA)2(μ-pzdc)(μ-η1:η1-O2)]ClO4·3H2O (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-η1:η1-peroxo (end-on) and the dicarboxylato pyrazole. The peroxo O–O and the Co⋯Co distances are 1.406(3) and 3.7632(5) Å, respectively, and the Co(III) centers are almost co-planar with the pzdc anion.