Exploring Synthetic Routes to Heteroleptic U III , U IV , and Th IV Bulky Bis(silyl)amide Complexes

The bis(silyl)amide {N(SiMe 3 ) 2 } (N′′) has supported spectacular actinide (An) chemistry for over 40 years, yet surprisingly there are only a handful of An complexes containing larger bis(silyl)amides, for example [U(N**) 3 ] [N** = {N(SiMe 2 t Bu) 2 }, 1 ]. Herein we report the structural characterization of the U III complexes [U(N**) 2 (µ‐I)] 2 ( 2 ), [U(N † ′) 2 (µ‐I)] 2 [N † ′ = {N(Si i Pr 3 )(SiMe 3 )}, 3 ], [U(N †† )( I ) 2 (THF) 2 ] [N †† = {N(Si i Pr 3 ) 2 }, 4 ], [U(N †† ) 2 ( I )] ( 5 ), and [U(N † ′) 2 ( I )(THF)] ( 6 ), and the An IV complexes [An(N**){N(SiMe 2 t Bu)(SiMe t BuCH 2 ‐κ 2 ‐ N , C )}(µ‐Cl)] 2 ( 7‐An , An = U, Th) and [Th(N**) 2 {N(SiMe 2 t Bu)(SiMe t BuCH 2 ‐κ 2 ‐ N , C )}] ( 8 ). Low crystalline yields were obtained in all cases, presumably due to facile cyclometallation. Although this precluded full characterization of U III 4 and 6 , and An IV 7 and 8 , for U III complexes 2 , 3 , and 5 yields were high enough to perform NMR, EPR, NIR/UV/Vis, and FTIR spectroscopy, elemental analysis, and magnetic measurements.