In closed-shell systems, the Kβ' feature is not observed. For this analysis, we compare the Kβ XES of 1 -4 with high-spin Co II (acetate)2 (s=3/2), low-spin cobaltocene (s=1/2), and low-spin Co III (acac)3, (s=0, acac = acetylacetonate) references. 1 and 2 exhibit asymmetry in the Kβ1,3 feature (~7648.5 eV) and a pronounced low-energy shoulder from the Kβ' (~7637.5 eV), which are characteristic of high-spin Co 2+ species (Figure ). The high-spin Co 2+ natures of 1 and 2 are unsurprising, since a tetrahedral ligand field results in a weak d-orbital splitting and rarely produces low-spin species. In contrast, the spectra for 3 and 4 show features characteristic of low-spin Co centers, with the Kβ1,3 feature (~7647.2 eV) showing minor asymmetry at lower energy.