Products Cited in Publications Worldwide Divergent reactivity of a cobalt complex with CF3 versus CH3 electrophiles

Divergent reactivity of a cobalt complex with CF3 versus CH3 electrophiles

Kuruppu, Sewwandi; Zou, Minzhu; Waldie, Kate M

DOI:

Abstract

We report the synthesis, characterization, and multielectron activity of the electron-rich cobalt complex 1 within the redox-active [Cp*Co(Ropda)] family (Cp* = pentamethylcyclopentadienyl, opda = o-phenylenediamide). By installing electron-donating methoxy-phenylene, N-ethyl, and Cp* groups into this architecture, the electronic properties of complex 1 are modulated, enabling the further tuning of the potential for reversible two-electron oxidation and achieving the most negative redox potential for this process in this family. We demonstrate that the addition of an electrophilic trifluoromethyl source to complex 1 results in the rapid formation of the monocationic [CoIII−CF3] complex 3, accompanied by the formal two-electron oxidation of the opda ligand to the benzoquinonediimine form. The structural metrics of this product closely resemble those of the dicationic [CoIII−MeCN] complex 2, which is independently obtained via chemical oxidation of complex 1 using two equivalents of a silver(I) salt. Alternatively, treatment of complex 1 with electrophilic methyl reagents does not yield the analogous [CoIII−CH3] complex. Instead, rapid and stoichiometric formation of hexamethylcyclopentadiene is observed, indicating that methyl addition to the Cp* ligand and dissociation from the metal is a dominant reaction pathway.

Keywords

Cobalt ; redox-active ligands ; coordination chemistry ; multielectron transfer ; electrophilic addition

Purchased from AmBeed