Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents

作者：Andreychuk Nicholas R; Ilango Sougandi; Vidjayacoumar Balamurugan; Emslie David J H^*; Jenkins Hilary A

来源：Organometallics, 2013, 32(5): 1466-1474.

DOI：10.1021/om301136f

Reaction of [(XA(2))UCl3{K(dme)(3))] (XA(2) = 4,5-bis(2,6-diisopropylanilino)-2,7-di-tert-butyl-9,9-dimethyl-xanthene) with 2 equiv of ((trimethylsilyl)methyl)lithium or neopentyllithium afforded red-orange [(XA(2))U(CH2SiMe3)(2)] (1) and dark red [(XA(2))U(CH2CMe3)(2)] (2), respectively. Reaction of 1 with an additional 1 equiv of LiCH2SiMe3 in THF yielded yellow [Li(THF)(x)][(XA(2))U(CH2SiMe3)(3)] (3), and reaction of [(XA(2))UCl3{K(dme)(3)}] with 3 equiv of methyllithium in dme afforded yellow [Li(dme)(3)][(XA(2))-UMe3] (4). Reaction of 1 with 2.1 equiv of LiCH2CMe3 in benzene resulted in rapid conversion to 2, with release of 2 equiv of LiCH2SiMe3. Similarly, reaction of 1 with 3.3 equiv of MeLi in THF provided 4 as the [Li(THF)(x)](+) salt, accompanied by 2 equiv of LiCH2SiMe3. These unusual alkyl exchange reactions resemble salt metathesis reactions, but with elimination of an alkyllithium instead of a lithium halide. Addition of a large excess of LiCH2SiMe3 to 2 or 4 did not generate detectable amounts of 1 by NMR spectroscopy, suggesting that the equilibrium in these reactions lies far to the side of complexes 2 and 4. In contrast, the reaction of [(XA(2))Th(CH2SiMe3)(2)] (1-Th) with 2.2 equiv of LiCH2CMe3 yielded an approximate 1:1:3:1 mixture of [(XA(2))Th(CH2CMe3)(2)] (2-Th), [(XA(2))Th(CH2SiMe3)(CH2CMe3)] (5-Th), LiCH2SiMe3, and LiCH2CMe3.

• 出版日期2013-3-11