%AMoreau, Liane%ALapsheva, Ekaterina%AAmaro-Estrada, Jorge%AGau, Michael%ACarroll, Patrick%AManor, Brian%AQiao, Yusen%AYang, Qiaomu%ALukens, Wayne%ASokaras, Dimosthenis%ASchelter, Eric%AMaron, Laurent%ABooth, Corwin%BJournal Name: Chemical Science; Journal Volume: 13; Journal Issue: 6 %D2022%I %JJournal Name: Chemical Science; Journal Volume: 13; Journal Issue: 6 %K %MOSTI ID: 10394993 %PMedium: X %TElectronic structure studies reveal 4f/5d mixing and its effect on bonding characteristics in Ce-imido and -oxo complexes %XThis study presents the role of 5d orbitals in the bonding, and electronic and magnetic structure of Ce imido and oxo complexes synthesized with a tris(hydroxylaminato) [((2- t BuNO)C 6 H 4 CH 2 ) 3 N] 3− (TriNO x 3− ) ligand framework, including the reported synthesis and characterization of two new alkali metal-capped Ce oxo species. X-ray spectroscopy measurements reveal that the imido and oxo materials exhibit an intermediate valent ground state of the Ce, displaying hallmark features in the Ce L III absorption of partial f-orbital occupancy that are relatively constant for all measured compounds. These spectra feature a double peak consistent with other formal Ce( iv ) compounds. Magnetic susceptibility measurements reveal enhanced levels of temperature-independent paramagnetism (TIP). In contrast to systems with direct bonding to an aromatic ligand, no clear correlation between the level of TIP and f-orbital occupancy is observed. CASSCF calculations defy a conventional van Vleck explanation of the TIP, indicating a single-reference ground state with no low-lying triplet excited state, despite accurately predicting the measured values of f-orbital occupancy. The calculations do, however, predict strong 4f/5d hybridization. In fact, within these complexes, despite having similar f-orbital occupancies and therefore levels of 4f/5d hybridization, the d-state distributions vary depending on the bonding motif (CeO vs. CeN) of the complex, and can also be fine-tuned based on varying alkali metal cation capping species. This system therefore provides a platform for understanding the characteristic nature of Ce multiple bonds and potential impact that the associated d-state distribution may have on resulting reactivity. %0Journal Article