A combination of Cu L-edge and S K-edge X-ray absorption data and density functional theory (DFT) calculations has been correlated with ³³S electron paramagnetic resonance superhyperfine results to obtain the dipole integral (I_s) for the S 1s→3p transition for the dithiolene ligand maleonitriledithiolate (MNT) in (TBA)₂[Cu(MNT)₂] (TBA= tetra-n-butylammonium). The results have been combined with the I_s of sulfide derived from XPS studies to experimentally obtain a relation between the S 1s→4p transition energy (which reflects the charge on the S atom, ) and the dipole integral over a large range of . The results show that, for high charges on S, I_s can vary from the previously reported I_s values, calculated using data over a limited range of . A combination of S K-edge and Cu K- and L-edge X-ray absorption data and DFT calculations has been used to investigate the one-electron oxidation of [Cu(MNT)₂]^2- and [Ni(MNT)₂]^2-. The conversion of [Cu(MNT)₂]^2- to [Cu(MNT)₂]^- results in a large change in the charge on the Cu atom in the molecule ( ) and is consistent with a metal-based oxidation. This is accompanied by extensive charge donation from the ligands to compensate the high charge on the Cu in [Cu(MNT)₂]^- based on the increased S K-edge and decreased Cu L-edge intensity, respectively. In contrast, the oxidation of [Ni(MNT)₂]^2- to [Ni(MNT)₂]^- results in a small change in , indicating a ligand-based oxidation consistent with oxidation of a molecular orbital, (singly occupied molecular orbital), with predominant ligand character.

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