51. Square-planar imido complexes of cobalt: synthesis, reactivity and computational study.
- Author
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Reyna, Jackson A., Krishnan, V. Mahesh, Silva Villatoro, Roberto, Arman, Hadi D., Stoian, Sebastian A., and Tonzetich, Zachary J.
- Subjects
SCHIFF bases ,ATOMS ,COBALT ,HYDROGEN atom ,DENSITY functional theory ,CATALYTIC activity ,AZIRIDINATION - Abstract
Treatment of [Co(N
2 )(tBu PNP)] (tBu PNP = anion of 2,5-bis(di-tert-butylphosphinomethyl)pyrrole) with one equivalent of an aryl azide generates the four-coordinate imido complexes [Co(NAr)(tBu PNP)] (Ar = mesityl, phenyl, or 4-t Bu-phenyl). X-ray crystallographic analysis of the compounds shows an unusual square-planar geometry about cobalt with nearly linear imido units. In the presence of the hydrogen atom donor, TEMPOH, [Co(NPh)(tBu PNP)] undergoes addition of the H atom to the imido nitrogen to generate the corresponding amido complex, [Co(NHPh)(tBu PNP)], whose structure and composition were verified by independent synthesis. Despite the observation of H atom transfer reactivity with TEMPOH, the imido complexes do not show catalytic activity for C–H amination or aziridination for several substrates examined. In the case of [Co(NPh)(tBu PNP)], addition of excess azide produced the tetrazido complex, [Co(N4 Ph2 )(tBu PNP)], whose bond metrics were most consistent with an anionic Ph2 N4 ligand. Density Functional Theory (DFT) investigations of the imido and tetrazido species suggest that they adopt a ground state best described as possessing a low-spin cobalt(II) ion ferromagnetically coupled to an iminyl radical. [ABSTRACT FROM AUTHOR]- Published
- 2024
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