Pseudo-octahedral nickel(ii) complexes of strongly absorbing benzannulated pincer-type amido ligands: ligand-based redox and non-Aufbau electronic behaviour

Jason D Braun; Issiah B Lozada; Michael Shepit; Johan van Lierop; David E Herbert

doi:10.1039/d0ra10761a

Pseudo-octahedral nickel(ii) complexes of strongly absorbing benzannulated pincer-type amido ligands: ligand-based redox and non-Aufbau electronic behaviour

RSC Adv. 2021 Jan 18;11(6):3547-3555. doi: 10.1039/d0ra10761a. eCollection 2021 Jan 14.

Authors

Jason D Braun¹, Issiah B Lozada¹, Michael Shepit², Johan van Lierop^{2

3}, David E Herbert^{1

3}

Affiliations

¹ Department of Chemistry, University of Manitoba 144 Dysart Road Winnipeg Manitoba Canada [email protected].
² Department of Physics and Astronomy, University of Manitoba 31A Sifton Rd Winnipeg Manitoba Canada.
³ Manitoba Institute for Materials, University of Manitoba 20 Sifton Rd Winnipeg MB Canada.

Abstract

The synthesis, structures and electronic characterization of three strongly coloured, pseudo-octahedral Ni(ii) complexes supported by redox-active diarylamido ligands featuring benzannulated N-heterocyclic donor arms are reported. The S = 1 paramagnets each present two singly occupied molecular orbitals (SOMOs) identified as metal-based by density functional theory (DFT), consistent with solid-state and solution magnetism measurements. Upon applying oxidative potentials, non-Aufbau behaviour leads to the appearance of intense and well-defined absorption features extending into the near IR (NIR). The attribution of these features to the onset of aminyl radical character through ligand-based redox is corroborated by exceptionally strong intervalence charge-transfer (IVCT) transitions ascribed to electronic communication between two N_amido moieties across a Ni(ii) bridge.