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Tuning Cobalt(II) Phosphine Complexes to be Axially Ambivalent

Thomas-Colwell, Jack and Sookezian, Arvin and Kurtz, Daniel A. and Kallick, Jeremy and Henling, Lawrence M. and Stich, Troy A. and Hill, Michael G. and Hunter, Bryan M. (2022) Tuning Cobalt(II) Phosphine Complexes to be Axially Ambivalent. Inorganic Chemistry, 61 (32). pp. 12625-12634. ISSN 0020-1669. doi:10.1021/acs.inorgchem.2c01562.

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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][BF₄]₂(1), [Co(dppv)₂(NCCH₃][BPh₄]₂(2), and [Co(dppv)₂(NCCH₃)₂][BF₄]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.

Item Type:Article
Related URLs:
URLURL TypeDescription
Kurtz, Daniel A.0000-0002-0082-1699
Stich, Troy A.0000-0003-0710-1456
Hunter, Bryan M.0000-0001-8559-9304
Additional Information:© 2022 The Authors. Published by American Chemical Society. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Received 6 May 2022. Published online 3 August 2022. D.A.K. thanks the Rowland Foundation, Inc. For a Rowland Postdoctoral Fellowship. B.M.H. is a Fellow of the Rowland Institute at Harvard. T.A.S. thanks the Wake Forest University for the financial support. The Bruker D8 Kappa X-ray diffractometer was purchased via an NSF CRIF:MU award to the California Institute of Technology (CHE-0639094). The authors declare no competing financial interest. CCDC 2166489–2166490 contain the supplementary crystallographic data for this paper.
Funding AgencyGrant Number
Rowland FoundationUNSPECIFIED
Harvard UniversityUNSPECIFIED
Wake Forest UniversityUNSPECIFIED
Subject Keywords:Cobalt, Electromagnetic radiation, Electron paramagnetic resonance spectroscopy, Group 15 compounds, Ligands
Issue or Number:32
Record Number:CaltechAUTHORS:20220803-536079000
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Official Citation:Tuning Cobalt(II) Phosphine Complexes to be Axially Ambivalent. Jack Thomas-Colwell, Arvin Sookezian, Daniel A. Kurtz, Jeremy Kallick, Lawrence M. Henling, Troy A. Stich, Michael G. Hill, and Bryan M. Hunter. Inorganic Chemistry 2022 61 (32), 12625-12634; DOI: 10.1021/acs.inorgchem.2c01562
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:116078
Deposited By: George Porter
Deposited On:09 Aug 2022 14:52
Last Modified:24 Aug 2022 21:21

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