Synthesis and structure of diamido ether uranium(IV) and thorium(IV) halide "ate" complexes and their conversion to salt-free bis(alkyl) complexes

The high-yield synthesis, spectroscopic and structural determination of three new uranium(IV) and thorium(IV) "ate" complexes supported by three different diamido ether ligands are reported. The reaction of Li-2[2,6-(Pr2PhN)-Pr-i(CH2CH2)](2)O (Li-2[(NCOCN)-N-DIPP]) with 1 equiv. of UCl4 in THF generates [(NCOCN)-N-DIPP] UCl3Li(THF)(2) ( 1), while reaction in toluene/ether gives salt-free [(NCOCN)-N-DIPP] UCl2 center dot 1/2 C7H8 (2), which was identified by paramagnetically shifted H-1 NMR. Reaction of 0.5 equiv. of {[(NON)-N-tBu] UCl2}(2) ([(NON)-N-tBu] = [(CH3)(3)CN(Si(CH3)(2))](2)O2-) with 3.5 equiv. LiI in toluene and a minimal amount of THF results in [(NON)-N-tBu] UI3Li(THF)(2) (3) and is very similar in structure to 1. {[(NON)-N-Mes] ThCl3Li(THF)}(2) ( 4), a dimeric complex with a Th2Li2Cl6 core, is prepared by reaction of Li-2[2,4,6-Me3PhN(Si(CH3)(2))](2)O (Li-2[(NON)-N-Mes]) with ThCl4 in THF. The analogous reaction in toluene did not yield the salt-free complex but rather a sterically crowded diligated compound, [(NON)-N-Mes](2)Th (5), which was also structurally characterized. Complex 5 was prepared rationally by reacting 2 equiv. Li2[ MesNON] with ThCl4 in toluene. The reaction of 1 and 3 with 2 equiv. of LiCH2Si(CH3)(3) generates the stable, salt-free organoactinides [(NCOCN)-N-DIPP] U(CH2Si(CH3)(3))(2) ( 6) and [(NON)-N-tBu] U(CH2Si(CH3)(3))(2) ( 7). Complex 6 was structurally characterized. These reactions illustrate the viability of "ate" complexes as useful synthetic precursors.