Lithium alkyl anions of uranium(IV) and uranium(V). Addition compounds of uranium(VI) hexaisopropoxide with lithium, magnesium, and aluminium alkyls

Organouranium compounds with six or eight uranium-to-carbon σ-bonds have been synthesized for the first time. The interaction of uranium tetrachloride with lithium alkyls in diethyl ether leads to the isolation of unstable lithium alkyluranate(IV) compounds of stoicheiometry Li₂UR₆·8Et₂O (R = Me, CH₂SiMe_3· Ph, and o-Me₂NCH₂C₆H₄). These lithium salts can also be obtained with other donor solvents, such as tetrahydrofuran or NNN′N′-tetramethyl-ethylenediamine. From uranium pentaethoxide similar lithium salts of stoicheiometry Li₃UR₈·3 dioxan (R = Me, CH₂CMe₃, and CH₂SiMe₃) can be obtained. The interaction of uranium(VI) hexaisopropoxide with lithium, magnesium, or aluminium alkyls does not give compounds containing U-C bonds, but green oils, e.g., U(Pr)₆(MgMe₂)₃, that appear to be adducts in which the oxygen atom of the isopropoxide group bound to uranium is acting as a donor. I.r. and n.m.r. spectroscopy and analytical data for the new compounds are presented.