Hard to Handle: Extremely Labile Hydrido Nickel(II) Complexes of Cyclometalated C N N and N C N Ligands

Lukas Kletsch, Leo Payen, Antonio Fiorentino, Burgert Blom, Dario Romano, Gerald Hoerner, Axel Klein*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

From the two organonickel(II) scaffolds [Ni(Phbpy)] + and [Ni(PyPhPy)] + (HPhbpy = 6-phenyl-2,2′-bipyridine≡HC N N and Py(HPh)Py = 2,6-di-2-pyridyl-benzene≡N (HC) N) the hydrido complexes [Ni(C N N)H] and [Ni(N C N)H] were studied in a combined experimental/theoretical approach. The hydrido complexes were prepared via the reaction of the halido derivatives [Ni(C N N)X] and [Ni(N C N)X] (X = Cl, Br) with Li(Et 3BH) (superhydride). The C N N complex undergoes rapid reductive elimination (RE) yielding HPhbpy and Ni particles even at the lowest temperatures, while the PyPhPy derivative is more stable. Low-temperature 1H nuclear magnetic resonance (NMR) spectroscopy allowed detection of a signal at δ = −2.86 ppm assignable to the hydrido ligand. The different stabilities can be directly correlated to the cis (Phbpy) and trans (PyPhPy) orientations of the carbanionic phen-2-ide group with the hydrido ligand, and rapid RE occurs from the cis position which is also supported by the density functional theory (DFT) calculations which are presented. A further TD-DFT/UV-vis absorption study is also reported to rationalize and confirm the fleeting existence of the Ni-H moiety, and proposals are made on the route of its decomposition.

Original languageEnglish
Pages (from-to)2206-2215
Number of pages10
JournalOrganometallics
Volume42
Issue number16
Early online date1 Aug 2023
DOIs
Publication statusPublished - 28 Aug 2023

Keywords

  • C-H BOND
  • OXIDATIVE ADDITION
  • PINCER COMPLEXES
  • REACTIVITY
  • ALKYLATION
  • HYDROGEN
  • NI
  • POLYMERIZATION
  • CATALYSTS
  • EXCHANGE

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