Summary of the vertical MC state energies derived from the Tanabe–Sugano analysis of the RIXS spectra of 1, 2 and 3 (Fig. 5). The scaling factor for 3d electron repulsion Racah parameters is 75%: B = 0.110 eV and C = 0.406 eV (see ESI for details).

Complex	10Dq (eV)	3T1g (eV)	3T2g (eV)	1T1g (eV)	1T2g (eV)
1	3.24	2.09	2.80	2.98	4.40
2	3.22	2.08	2.78	2.97	4.38
3	3.19	2.04	2.75	2.93	4.34
Average	3.22	2.07	2.78	2.96	4.38