Synthesis, Characterization, and Organometallic Derivatives of Diamidosilyl Ether Thorium(IV) and Uranium(IV) Halide Complexes

The high-yield synthesis and spectroscopic and structural characterization of two new
dimeric uranium(IV) and thorium(IV) halide complexes {[tBuNON]AnCl2}2 (An = U (1), Th
(2)) supported by the doubly deprotonated diamidosilyl ether ligand [(CH3)3CNH(Si(CH3)2)]2O
([tBuNON]2-) are reported. The reaction of 1/2 equiv of 1 or 2 with 2 equiv of LiCH2Si(CH3)3
or C3H5MgCl generates stable organoactinides of the form [tBuNON]AnR2 (R = C3H5, An =
U (3), Th (4); R = CH2Si(CH3)3, An = U (5), Th (6)). The reaction of 1/2 equiv of 1 or 2 with
1 equiv of Na(C5(CH3)5) results in [tBuNON]An(η5-C5(CH3)5)Cl (An = U (7), Th (8)), which
can be converted to the mixed amido/Cp complex [tBuNON]An(C5(CH3)5)CH3 (An = U (9), Th
(10)) by reaction with CH3MgBr. The uranium(IV) complexes were characterized by
paramagnetically shifted 1H NMR spectra; the U−CH2 and U−CH3 resonances for 5 and 9
are at δ −148.9 and −146.3, respectively. The 1H and 13C{1H} NMR spectra of the thorium(IV) complexes are also consistent with these formulations; the Th−CH2 resonances in 6
are at δ 0.0 and 85.58 for 1H and 13C{1H}, respectively. The variable-temperature magnetic
susceptibilities of the uranium(IV) halide dimer 1 and monomer 7 are also reported.