Chromium acetate and formate complexes have been studied extensively, in contrast to their structurally analogous pyrazolates. The latter have now been prepared by a microwave assisted synthetic procedure: The reaction of Cr(NO3)3.9H2O and pyrazole in dimethylformamide (DMF) solution afforded redox inactive trinuclear formate-pyrazolate mixed-ligand complexes with formula [Cr3(μ3-O)(μ-O2CH)3(μ-4-R-pz)3(DMF)3]+ (pz = pyrazolato anion; R = H, Me, Cl). Thermally assisted synthesis in a non-hydrolyzable solvent yielded an electrochemically active all-pyrazolate complexes (Ph4P)2[Cr3(μ3-O)(μ-4-Cl-pz)6Cl3] (1) and (Ph4P)2[Cr3(μ3-O)(μ-4-Cl-pz)6Br3] (2), which have reversible one-electron oxidation processes at 0.502 V and 0.332 V, respectively. The tribromo complex has in addition a second oxidation process at 0.584 V. The low lability of pyrazolates provides an advantage over the carboxylate analogs with regard to electrochemical studies. Complexes 1 and 2 are the first example of electrochemically amendable trinuclear pyrazolate complex with {Cr3O} core.

Synthesis and characterization of pyrazolate supported CrIII3(μ3-O) cores

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.