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Tuning Cobalt(II) Phosphine Complexes to be Axially Ambivalent

[Image: see text] We report the isolation and characterization of a series of three cobalt(II) bis(phosphine) complexes with varying numbers of coordinated solvent ligands in the axial position. X-ray quality crystals of [Co(dppv)(2)][BF(4)](2)(1), [Co(dppv)(2)(NCCH(3))][BPh(4)](2)(2), and [Co(dppv)...

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Detalles Bibliográficos
Autores principales: Thomas-Colwell, Jack, Sookezian, Arvin, Kurtz, Daniel A., Kallick, Jeremy, Henling, Lawrence M., Stich, Troy A., Hill, Michael G., Hunter, Bryan M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9387527/
https://www.ncbi.nlm.nih.gov/pubmed/35920800
http://dx.doi.org/10.1021/acs.inorgchem.2c01562
Descripción
Sumario:[Image: see text] We report the isolation and characterization of a series of three cobalt(II) bis(phosphine) complexes with varying numbers of coordinated solvent ligands in the axial position. X-ray quality crystals of [Co(dppv)(2)][BF(4)](2)(1), [Co(dppv)(2)(NCCH(3))][BPh(4)](2)(2), and [Co(dppv)(2)(NCCH(3))(2)][BF(4)](2)(3) (dppv = cis-1,2-bis(diphenylphosphino)ethylene) were grown under slightly different conditions, and their structures were compared. This analysis revealed multiple crystallization motifs for divalent cobalt(II) complexes with the same set of phosphine ligands. Notably, the 4-coordinate complex 1 is a rare example of a square-planar cobalt(II) complex, the first crystallographically characterized square-planar Co(II) complex containing only neutral, bidentate ligands. Characterization of the different axial geometries via EPR and UV–visible spectroscopies showed that there is a very shallow energy landscape for axial ligation. Ligand field angular overlap model calculations support this conclusion, and we provide a strategy for tuning other ligands to be axially labile on a phosphine scaffold. This methodology is proposed to be used for designing cobalt phosphine catalysts for a variety of oxidation and reduction reactions.