Structure, magnetic properties and electronic structure of a nickel(II) complex with redox-active 6-(8-quinolylamino)-2,4-bis(tert-butyl)phenol
作者:Molina A.L. Sheepwash、Alan J. Lough、Lorenzo Poggini、Giordano Poneti、Martin T. Lemaire
DOI:10.1016/j.poly.2015.06.010
日期:2016.3
We report the preparation and electronic structure of a nickel complex 2 containing ligand 6-(8-quinolylamino)-2,4-bis(tert-butyl)phenol 1. The complex is neutral, six-coordinate (pseudo-octahedral) and homoleptic containing two equivalents of 1 and no counteranions. The bond distances measured by single crystal X-ray diffraction studies suggest that the two equivalents of I are bound as mono-anion radicals (iminosemiquinone oxidation state). Variable temperature magnetic susceptibility data indicates a quintet (S = 2) ground state for this complex resulting from ferromagnetic coupling between Ni2+ and the coordinated radical anions. Cyclic voltammetry experiments and UV-Vis-NIR spectroscopy indicate the presence of coordinated iminosemiquinone radicals, and these experimental results are corroborated by density functional theory calculations, which support the proposed assignments. Complex 2 is easily oxidized in the presence of ferrocenium hexafluorophosphate or aerial dioxygen to produce a complex with closed shell ligands and spectroscopic features characteristic of ortho-iminoquinone ligands. (C) 2015 Elsevier Ltd. All rights reserved.