Synthesis and structure of the first uranium(VI) organometallic complex

Perturbation of the O–U–O Angle in Uranyl by Coordination to a 12-Membered Macrocycle

“…4,9,10 Their higher stability, relative to the unobserved oxo analogue, is probably due to a greater reliance on -bonding within the [U(NR) 2 ] 2+ fragment, which diminishes the importance of the 6p orbital participation in the -bonding framework. 11 Similarly, Arnold and co-workers recently reported the isolation of 4 [ (c) 0.5 + 2 bipy Scheme 1.…”

Preparation and Reactions of Base-Free Bis(1,2,4-tri-tert-butylcyclopentadienyl)uranium Methylimide, Cp‘2UNMe, and Related Compounds

“…Several substituted cyclopentadienyl uranium-imido derivatives of the type (η 5 -C 5 Me 5 ) 2 U(NAr) 2 , (η 5 -C 5 Me 5 ) 2 U(NAr)(O), (η 5 -MeC 5 H 4 ) 3 U=NPh and (η 5 -C 5 Me 5 ) 2 U=NAr have been prepared. [1][2][3][4][5][6][7][8][9][10] When the arylamine has sterically bulky substituents such as i-Pr and t-Bu in the 2,6-positions, 3,4 the (η 5 -C 5 Me 5 ) 2 U=NAr derivatives are generally prepared by reaction of (η 5 -C 5 Me 5 ) 2 UMe 2 with one equiv of a primary arylamine, which presumably forms (η 5 -C 5 Me 5 ) 2 U(Me)(NHAr), which eliminates methane forming the imidometallocene.…”

“…[1][2][3][4][5][6][7][8][9][10] When the arylamine has sterically bulky substituents such as i-Pr and t-Bu in the 2,6-positions, 3,4 the (η 5 -C 5 Me 5 ) 2 U=NAr derivatives are generally prepared by reaction of (η 5 -C 5 Me 5 ) 2 UMe 2 with one equiv of a primary arylamine, which presumably forms (η 5 -C 5 Me 5 ) 2 U(Me)(NHAr), which eliminates methane forming the imidometallocene. 3,4 When the substituents are somewhat less bulky, for example 2,6-dimethylaniline, the bis-amide derivative is formed, which thermally eliminates the amine forming (η 5 -C 5 Me 5 ) 2 U(NAr)(thf).…”

“…3,4 When the substituents are somewhat less bulky, for example 2,6-dimethylaniline, the bis-amide derivative is formed, which thermally eliminates the amine forming (η 5 -C 5 Me 5 ) 2 U(NAr)(thf). 8,9 However, the least bulky arylamine, aniline, yields (η 5 -C 5 Me 5 ) 2 U(NHPh) 2 , which is stable to elimination of aniline. 4 The primary alkylamines, EtNH 2 and Me 3 CNH 2 , behave similarly.…”

“…The formation of a metallocene imide from a metallocene bis(amide) is an important reaction since it is postulated to be a key step in the catalytic hydroamination of terminal acetylenes reported by Eisen. 10 The decamethylmetalloceneuranium fragment 11 is essential for the preparation of these monomeric f 2 -imido derivatives (with or without a coordinated Lewis base), since for example, imides derived from (η 5 -MeC 5 H 4 ) 2 U or [(Me 3 Si) 2 N] 2 U fragments yield dimeric derivatives, (η 5 -MeC 5 H 4 ) 4 U 2 (μ-NR) 2 12 or [(Me 3 Si) 2 N] 4 U 2 (μ-NR) 2 . 13 Thus, steric effects seem to play a dominant role in determining the degree of association of the uranium imide.…”