Halogen-Bonding Interactions and Electrochemical Properties of Unsymmetrical Pyrazole Pincer NiII Halides: A Peculiar Behavior of the Fluoride Complex (PCN)NiF

Luconi, Lapo; Garino, Claudio; Cerreia Vioglio, Paolo; Gobetto, Roberto; Chierotti, Michele R.; Yakhvarov, Dmitry; Gafurov, Zufar N.; Morozov, Vladimir; Sakhapov, Il’yas; Rossin, Andrea; Giambastiani, Giuliano

Abstract

Four metal halides of the (tBuPCN)NiX family [X = F (1), Cl (2), Br (3), or I (4); PCN = 1-[3-[(di-tert-butylphosphino)methyl]phenyl]-1H-pyrazole] have been prepared through a direct reaction of the corresponding anhydrous NiX2 salts and the unsymmetrical PCN pincer ligand. Structural information from single-crystal X-ray data, 19F solution nuclear magnetic resonance, and combined electrochemical results [cyclic voltammetry (CV) and in situ electron paramagnetic resonance spectro-electrochemistry] reveal that the fluoride complex 1 is different from the other halides 2–4 in terms of electro-oxidation behavior (presence of three anodic peaks instead of one in the CV profile). 1 is also different from its symmetrical analogue (tBuPCP)NiF in terms of halogen-bonding capability toward the halogen-bond donor, iodopentafluorobenzene (C6F5I, IPFB). The positive ΔS° value for the formation of the 1···IPFB adduct inferred from the van’t Hoff plots is in agreement with the existence of (1·H2O) aggregates in solution, not present in 2–4. The high nucleophilicity of the fluoride ligand and the simultaneous presence of electrophilic (acidic) protons on the sidearm of the pyrazole ligand are at the origin of the observed phenomena.

Citation

Luconi, L., Garino, C., Cerreia Vioglio, P., Gobetto, R., Chierotti, M. R., Yakhvarov, D., Gafurov, Z. N., Morozov, V., Sakhapov, I., Rossin, A., & Giambastiani, G. (2019). Halogen-Bonding Interactions and Electrochemical Properties of Unsymmetrical Pyrazole Pincer NiII Halides: A Peculiar Behavior of the Fluoride Complex (PCN)NiF. ACS Omega, 4(1), 1118-1129. https://doi.org/10.1021/acsomega.8b02452

• Journal Article Type: Article
• Acceptance Date: Dec 20, 2018
• Online Publication Date: Jan 14, 2019
• Publication Date: Jan 31, 2019
• Deposit Date: Nov 18, 2024
• Publicly Available Date: Nov 25, 2024
• Journal: ACS Omega
• Electronic ISSN: 2470-1343
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 1
• Pages: 1118-1129
• DOI: https://doi.org/10.1021/acsomega.8b02452
• Keywords: Anions, Halogens, Inorganic compounds, Ligands, Oxidation
• Public URL: https://nottingham-repository.worktribe.com/output/41934190
• Publisher URL: https://pubs.acs.org/doi/10.1021/acsomega.8b02452