Revisiting cobaloxime(<scp>ii</scp>) chemistry and clearing misconceptions of cobaloxime(<scp>ii</scp>) in diamagnetic Ni(<scp>ii</scp>) and Pd(<scp>ii</scp>) matrixes using comprehensive magnetic measurements

Co(II) was doped into the diamagnetic one-dimensional framework of bis(dimethylglyoximato) Ni(II) and Pd(II) complexes [Ni/Pd^II(Hdmg)₂] (Hdmg = dimethylglyoximate anion) (hereafter referred to as Co@Ni and Co@Pd samples) to study magnetic properties as a potential spin qubit. In a previous report of electron paramagnetic resonance (EPR) spectroscopy of this compound prepared using the same doping strategy in the Ni matrix, a spectrum assigned to <i>S</i> = 1/2 Co(II) with <i>g</i>_<i>x</i> = 2.58, <i>g</i>_<i>y</i> = 2.26 <i>g</i>_<i>z</i> = 1.98 was observed. The relatively large <i>g</i>_<i>x</i> value, compared to those typically observed in [Co(Hdmg)₂B_<i>x</i>] complexes (B = Lewis base ligand, <i>x</i> = 1 or 2), which fall within the ranges <i>g</i>_<i>x</i> = 2.1-2.4, <i>g</i>_<i>y</i> = 2.0-2.2 and <i>g</i>_<i>z</i> ≈ 2.01, led to the interpretation of this species to be Co(Hdmg)₂ with an extremely axial interaction. However, our EPR analysis, combined with SQUID (superconducting quantum interference device) and XANES (X-ray absorption near-edge structure) analyses, revealed that the previously identified species are μ-O bridged dimers: [Co(Hdmg)(μ-Hdmg)]₂ and [Co(Hdmg)(μ-Hdmg)][Ni/Pd(Hdmg)(μ-Hdmg)]. Furthermore, our liquid-helium temperature EPR spectra revealed a Co species with much greater axial <i>g</i> anisotropy (<i>g</i>_<i>x</i> = 4.75 <i>g</i>_<i>y,z</i> ≈ 0.75 for Co@Ni and <i>g</i>_<i>x</i> = 4.2 <i>g</i>_<i>y,z</i> ≈ 1.33 for Co@Pd). We assign this species to the truly planar Co(Hdmg)₂ with negligibly weak axial interaction, which might have been overlooked in previous EPR studies.